def check(S, T):
    N = len(S)
    i = 0
    j = 0
    memo = 0
    while i < N:
        if S[i] == T[j]:
            i += 1
            j += 1
        elif memo == 0:
            memo = (i, T[j])
            i += 1
        else:
            return False, -1
    return True, memo


def main():
    N, M = map(int, input().split())
    S = input()
    T = input()
    U = [input() for _ in range(N - 2)]

    b1, m1 = check(S, T)
    b2, m2 = check(T, S)

    res = 0
    for _ in range(2):
        b, m = check(S, T)
        if b:
            i, c = m
            X = S[:i] + c + S[i:]
            ok = True
            for u in U:
                bb, mm = check(X, u)
                if not bb:
                    ok = False
                    break
            res += ok
        S, T = T, S
    return res


print(main())