[소프티어] CPTI

import sys

n, m = map(int, input().split())

ppl = []

for i in range(n):
    ppl.append(str(input()))

answer = 0

for i in range(n):
    for j in range(i+1, n):
        temp = 0
        for k in range(m):
            if ppl[i][k] != ppl[j][k]:
                temp += 1
            if temp > 2:
                break
        if temp <= 2:
            answer +=1

print(answer)