You are given three strings A, B and C. Each of these is a string of length N consisting of lowercase English letters.

Our objective is to make all these three strings equal. For that, you can repeatedly perform the following operation:

* Operation: Choose one of the strings A, B and C, and specify an integer i between 1 and N (inclusive). Change the i-th character from the beginning of the chosen string to some other lowercase English letter.



What is the minimum number of operations required to achieve the objective?

Constraints

* 1 \leq N \leq 100
* Each of the strings A, B and C is a string of length N.
* Each character in each of the strings A, B and C is a lowercase English letter.

Input

Input is given from Standard Input in the following format:


N
A
B
C


Output

Print the minimum number of operations required.

Examples

Input

4
west
east
wait


Output

3


Input

9
different
different
different


Output

0


Input

7
zenkoku
touitsu
program


Output

13
n = input()
A = raw_input()
B = raw_input()
C = raw_input()
a = list(A)
b = list(B)
c = list(C)
count = 0
for i in range(0,n):
	if(a[i] == b[i]):
		if(a[i] == c[i]):
			pass
		else:
			c[i] = a[i]
			count+=1
	elif(a[i] == c[i]):
		b[i] = a[i]	
		count+=1
	elif(b[i] == c[i]):
		a[i] = b[i]
		count += 1
	else:
		b[i] = a[i]
		c[i] = a[i]
		count += 2
print(count)