import sys
sys.setrecursionlimit(1000100)

n, m = map(int, input().split())
lst = [input() for _ in range(n)]
S = lst[0]
T = lst[1]
tmp = []
ans = 0

def ok():
    for S in lst:
        p = 0
        for t in tmp:
            if S[p] == t:
                p += 1
                if p == m:
                    break
        if p != m:
            return False
    return True
    

def dfs(sp, tp, x):
    if sp == m and tp == m:
        global ans
        if ok():
            ans += 1
        return
    if sp < m and tp < m and S[sp] == T[tp]:
        tmp.append(S[sp])
        dfs(sp + 1, tp + 1, x)
        tmp.pop()
    else:
        if sp < m and not x & 1:
            tmp.append(S[sp])
            dfs(sp + 1, tp, x ^ 1)
            tmp.pop()
        if tp < m and not x & 2:
            tmp.append(T[tp])
            dfs(sp, tp + 1, x ^ 2)
            tmp.pop()

dfs(0, 0, 0)
print(ans)