Theatre Square in the capital city of Berland has a rectangular shape with the size *n* × *m* meters. On the occasion of the city's anniversary, a decision was taken to pave the Square with square granite flagstones. Each flagstone is of the size *a* × *a*.

What is the least number of flagstones needed to pave the Square? It's allowed to cover the surface larger than the Theatre Square, but the Square has to be covered. It's not allowed to break the flagstones. The sides of flagstones should be parallel to the sides of the Square.
The input contains three positive integer numbers in the first line: *n*,  *m* and *a* (1 ≤  *n*, *m*, *a* ≤ 10<sup class="upper-index">9</sup>).
6 6 4
4
1 1 1
1
2 1 1
2
1 2 1
2
2 2 1
4
2 1 2
1
1 1 3
1
2 3 4
1
1000000000 1000000000 1
1000000000000000000
12 13 4
12
222 332 5
3015
1000 1000 10
10000
1001 1000 10
10100
100 10001 1000000000
1
1000000000 1000000000 1000000000
1
1000000000 1000000000 999999999
4
1000000000 1000000000 192
27126743055556
1000000000 987654321 1
987654321000000000
456784567 1000000000 51
175618850864484
39916800 134217728 40320
3295710
# LUOGU_RID: 126215250
import random, sys, os, math, gc
from collections import Counter, defaultdict, deque
from functools import lru_cache, reduce, cmp_to_key
from itertools import accumulate, combinations, permutations, product
from heapq import nsmallest, nlargest, heapify, heappop, heappush
from string import ascii_lowercase, ascii_uppercase
from io import BytesIO, IOBase
from copy import deepcopy
from bisect import bisect_left, bisect_right
from math import factorial, gcd,fabs
from operator import mul, xor
from types import GeneratorType

#sys.setrecursionlimit()
BUFSIZE = 8192
MOD = 10**9 + 7
MODD = 998244353
INF = float('inf')

class FastIO(IOBase):
    newlines = 0

    def __init__(self, file):
        self._fd = file.fileno()
        self.buffer = BytesIO()
        self.writable = "x" in file.mode or "r" not in file.mode
        self.write = self.buffer.write if self.writable else None

    def read(self):
        while True:
            b = os.read(self._fd, max(os.fstat(self._fd).st_size, BUFSIZE))
            if not b:
                break
            ptr = self.buffer.tell()
            self.buffer.seek(0, 2), self.buffer.write(b), self.buffer.seek(ptr)
        self.newlines = 0
        return self.buffer.read()

    def readline(self):
        while self.newlines == 0:
            b = os.read(self._fd, max(os.fstat(self._fd).st_size, BUFSIZE))
            self.newlines = b.count(b"\n") + (not b)
            ptr = self.buffer.tell()
            self.buffer.seek(0, 2), self.buffer.write(b), self.buffer.seek(ptr)
        self.newlines -= 1
        return self.buffer.readline()

    def flush(self):
        if self.writable:
            os.write(self._fd, self.buffer.getvalue())
            self.buffer.truncate(0), self.buffer.seek(0)
class IOWrapper(IOBase):
    def __init__(self, file):
        self.buffer = FastIO(file)
        self.flush = self.buffer.flush
        self.writable = self.buffer.writable
        self.write = lambda s: self.buffer.write(s.encode("ascii"))
        self.read = lambda: self.buffer.read().decode("ascii")
        self.readline = lambda: self.buffer.readline().decode("ascii")

sys.stdin = IOWrapper(sys.stdin)
# sys.stdout = IOWrapper(sys.stdout)
input = lambda: sys.stdin.readline().rstrip("\r\n")
# input = BytesIO(os.read(0, os.fstat(0).st_size)).readline

def py(): print('YES')
def pn():print('NO')
def I():
    return input()
def II():
    return int(input())
def MII():
    return map(int, input().split())
def MSI():
    return map(str,input().split())
def LI():
    return list(input().split())
def LII():
    return list(map(int, input().split()))
def MFI():
    return map(float,input().split())
def LFI():
    return list(map(float,input().split()))

n,m,a = MII()
res = math.ceil(n/a)+math.ceil(m/a)

print(res)
