Having written another programming contest, three Rabbits decided to grab some lunch. The coach gave the team exactly k time units for the lunch break.

The Rabbits have a list of n restaurants to lunch in: the i-th restaurant is characterized by two integers fi and ti. Value ti shows the time the Rabbits need to lunch in the i-th restaurant. If time ti exceeds the time k that the coach has given for the lunch break, then the Rabbits' joy from lunching in this restaurant will equal fi - (ti - k). Otherwise, the Rabbits get exactly fi units of joy.

Your task is to find the value of the maximum joy the Rabbits can get from the lunch, depending on the restaurant. The Rabbits must choose exactly one restaurant to lunch in. Note that the joy value isn't necessarily a positive value. 

Input

The first line contains two space-separated integers — n (1 ≤ n ≤ 104) and k (1 ≤ k ≤ 109) — the number of restaurants in the Rabbits' list and the time the coach has given them to lunch, correspondingly. Each of the next n lines contains two space-separated integers — fi (1 ≤ fi ≤ 109) and ti (1 ≤ ti ≤ 109) — the characteristics of the i-th restaurant.

Output

In a single line print a single integer — the maximum joy value that the Rabbits will get from the lunch. 

Examples

Input

2 5
3 3
4 5


Output

4


Input

4 6
5 8
3 6
2 3
2 2


Output

3


Input

1 5
1 7


Output

-1
import java.io.*;
import java.util.*;
import java.util.zip.ZipEntry;
import java.math.*;

public class Main {
	public static void main(String[] args) {
		InputStream inputStream = System.in;
		OutputStream outputStream = System.out;
		Input in = new Input(inputStream);
		PrintWriter out = new PrintWriter(outputStream);
		Task solver = new Task();
		solver.solve(1, in, out);
		out.close();
	}
}

class Task {
	static final long MOD = 1000000007;
	int[] primes;

	public void solve(int testNumber, Input in, PrintWriter out) {
		int n = in.nextInt();
		long k = in.nextLong();
		long ans = Long.MIN_VALUE;
		for (int i = 0; i < n; i++) {
			long f = in.nextLong();
			long t = in.nextLong();
			if (t > k) {
				ans = Math.max(ans, f - t + k);
			} else {
				ans = Math.max(ans, f);
			}
		}
		out.println(ans);
	}

	// didn't test
	static class BIT {
		int[] MAX;
		int[] MIN;
		int[] SUM;
		int n;

		public BIT(int n) {
			MAX = new int[n + 1];
			MIN = new int[n + 1];
			SUM = new int[n + 1];
			this.n = n;
		}

		public void setSum(int pos, int val) {
			for (int i = pos; i < n; i += (i & -i)) {
				SUM[i] += val;
			}
		}

		public int getSum(int to) {
			int sum = 0;
			for (int i = to; i > 0; i -= (i & -i)) {
				sum += SUM[i];
			}
			return sum;
		}

		public int getSum(int from, int to) {
			return getSum(to) - getSum(from);
		}

		public void setMax(int pos, int val) {
			for (int i = pos; i < n; i += (i & -i)) {
				MAX[i] = Math.max(val, MAX[i]);
			}
		}

		public int getMax(int to) {
			int max = 0;
			for (int i = to; i > 0; i -= (i & -i)) {
				max = Math.max(max, MAX[i]);
			}
			return max;
		}

		public void setMin(int pos, int val) {
			for (int i = pos; i < n; i += (i & -i)) {
				MIN[i] = Math.min(val, MIN[i]);
			}
		}

		public int getMin(int to) {
			int min = 0;
			for (int i = to; i > 0; i -= (i & -i)) {
				min = Math.min(min, MIN[i]);
			}
			return min;
		}

	}

	// didn't test
	static class DisjointSet {
		int[] set;

		public DisjointSet(int n) {
			set = new int[n];
			for (int i = 0; i < n; i++) {
				set[i] = i;
			}
		}

		public int findSet(int a) {
			if (set[a] == a)
				return a;
			return findSet(set[a]);
		}

		public void unionSet(int a, int b) {
			set[findSet(a)] = findSet(b);
		}

		public boolean isSameSet(int a, int b) {
			return findSet(a) == findSet(b);
		}
	}

	static class SegmentTree {
		int[] MAX;
		int[] MIN;
		int[] SUM;
		int[] data;
		int n;

		public SegmentTree(int[] data) {
			this.n = data.length;
			this.data = data;
			MAX = new int[4 * n + 10];
			MIN = new int[4 * n + 10];
			SUM = new int[4 * n + 10];
			buildTree(1, 0, n - 1);
		}

		public int left(int root) {
			return root << 1;
		}

		public int right(int root) {
			return (root << 1) + 1;
		}

		private void buildTree(int root, int rl, int rr) {
			if (rr == rl) {
				MAX[root] = MIN[root] = SUM[root] = data[rr];
			} else {
				int rm = (rl + rr) >> 1;
				buildTree(left(root), rl, rm);
				buildTree(right(root), rm + 1, rr);
				MAX[root] = Math.max(MAX[left(root)], MAX[right(root)]);
				MIN[root] = Math.min(MIN[left(root)], MIN[right(root)]);
				SUM[root] = SUM[left(root)] + SUM[right(root)];
			}
		}

		public int getMax(int from, int to) {
			return getMax(1, 0, n - 1, from, to);
		}

		private int getMax(int root, int rl, int rr, int from, int to) {
			if (from > rr || to < rl || rl > rr) {
				return -1;
			}
			if (from == rl && to == rr) {
				return MAX[root];
			}
			int rm = (rr + rl) >> 1;
			int m1 = getMax(left(root), rl, rm, from, Math.min(to, rm));
			int m2 = getMax(right(root), rm + 1, rr, Math.max(from, rm + 1), to);
			return Math.max(m1, m2);
		}

		public int getMin(int from, int to) {
			return getMin(1, 0, n - 1, from, to);
		}

		private int getMin(int root, int rl, int rr, int from, int to) {
			if (from > rr || to < rl || rl > rr) {
				return Integer.MAX_VALUE;
			}
			if (from == rl && to == rr) {
				return MIN[root];
			}
			int rm = (rr + rl) >> 1;
			int m1 = getMin(left(root), rl, rm, from, Math.min(to, rm));
			int m2 = getMin(right(root), rm + 1, rr, Math.max(from, rm + 1), to);
			return Math.min(m1, m2);
		}

		public int getSum(int from, int to) {
			return getSum(1, 0, n - 1, from, to);
		}

		private int getSum(int root, int rl, int rr, int from, int to) {
			if (from > rr || to < rl || rl > rr) {
				return 0;
			}
			if (from == rl && to == rr) {
				return SUM[root];
			}
			int rm = (rr + rl) >> 1;
			int m1 = getSum(left(root), rl, rm, from, Math.min(to, rm));
			int m2 = getSum(right(root), rm + 1, rr, Math.max(from, rm + 1), to);
			return m1 + m2;
		}
	}

	private String lcs(String s1, String s2) {
		int n = s1.length();
		int m = s2.length();
		int[][] dp = new int[n + 1][m + 1];
		for (int i = 1; i <= n; i++) {
			for (int j = 1; j <= m; j++) {
				if (s1.charAt(i - 1) == s2.charAt(j - 1)) {
					dp[i][j] = dp[i - 1][j - 1] + 1;
				} else {
					dp[i][j] = Math.max(dp[i - 1][j], dp[i][j - 1]);
				}
			}
		}
		StringBuilder sb = new StringBuilder();
		int i = n;
		int j = m;
		while (i > 0 && j > 0) {
			if (s1.charAt(i - 1) == s2.charAt(j - 1)) {
				sb.append(s1.charAt(i - 1));
				i--;
				j--;
			} else {
				if (dp[i - 1][j] > dp[i][j - 1]) {
					i--;
				} else {
					j--;
				}
			}
		}
		return sb.reverse().toString();
	}

	private boolean isPrime(int n) {
		if (n <= 3)
			return n > 1;
		else if (n % 3 == 0 || n % 2 == 0)
			return false;
		for (long i = 5; i * i <= n; i += 6) {
			if (n % i == 0 || n % (i + 2) == 0)
				return false;
		}
		return true;
	}

	private int[] getPrimes(int n) {
		int len = n + 1;
		boolean[] isPrimes = new boolean[len];
		int[] temps = new int[len];
		int index = 0;
		Arrays.fill(isPrimes, true);
		isPrimes[0] = isPrimes[1] = false;
		for (int i = 2; i * i < len; i++) {
			if (isPrimes[i]) {
				for (int j = i * i; j < len; j += i) {
					isPrimes[j] = false;
				}
			}
		}
		for (int i = 0; i < len; i++) {
			if (isPrimes[i])
				temps[index++] = i;
		}
		int[] primes = Arrays.copyOf(temps, index);
		return primes;
	}

	static void swap(char[] arrays, int pos1, int pos2) {
		char tmp = arrays[pos1];
		arrays[pos1] = arrays[pos2];
		arrays[pos2] = tmp;
	}

	static void swap(int[] arrays, int pos1, int pos2) {
		int tmp = arrays[pos1];
		arrays[pos1] = arrays[pos2];
		arrays[pos2] = tmp;
	}

	static long modPow(long n, long ex) {
		long res = 1;
		while (ex > 0) {
			if ((ex & 1) == 1)
				res = res * n % MOD;
			n = n * n % MOD;
			ex >>= 1;
		}
		return res;
	}

	static long ModInverse(long n) {
		return modPow(n, MOD - 2);
	}

	static long nCr(int n, int r) {
		if (r > n)
			return -1;
		// return (f[n] * ModInverse((f[r] * f[n - r]) % MOD)) % MOD;
		return 0;
	}
}

class Input {
	public BufferedReader reader;
	public StringTokenizer tokenizer;

	public Input(InputStream stream) {
		reader = new BufferedReader(new InputStreamReader(stream), 32768);
		tokenizer = null;
		tokenizer = null;
	}

	public String next() {
		while (tokenizer == null || !tokenizer.hasMoreTokens()) {
			try {
				tokenizer = new StringTokenizer(reader.readLine());
			} catch (IOException e) {
				throw new RuntimeException(e);
			}
		}
		return tokenizer.nextToken();
	}

	public int nextInt() {
		return Integer.parseInt(next());
	}

	public long nextLong() {
		return Long.parseLong(next());
	}

	public double nextDouble() {
		return Double.parseDouble(next());
	}
}
