#include <iostream>
#include <vector>
#include <algorithm>
#include <cstring>
#include <map>
using namespace std;
typedef long long ll;
int n, k;

int letter[16][6], cnt[16], D;
int pos_bitmask[6][26];
int row_use[16];

ll res = 0;
void rec(int x, const int * col_mask) {
    if(x == n) {
        vector<int> used(16);
        for(int i = 0; i < D; i++) {
            used[i] = row_use[i];
        }
        for(int j = 0; j < n; j++) {
            int idx = __builtin_ctz(col_mask[j]);
            used[idx]++;
            if(used[idx] > cnt[idx]) {
                return;
            }

        }
        res++;
        return;
    }

    for(int r = 0; r < D; r++) {
        if(row_use[r] + 1 > cnt[r]) continue;
        int new_col_mask[6];
        bool ok = true;
        for(int j = 0; j < n; j++) {
            int new_mask = col_mask[j] & pos_bitmask[x][letter[r][j]];
            if(new_mask == 0) {
                ok = false;
                break;
            }
            new_col_mask[j] = new_mask;
        }
        if(!ok) continue;

        row_use[r]++;
        rec(x + 1, new_col_mask);
        row_use[r]--;
    }

}
int main() {
    ios_base::sync_with_stdio(false);
    cin >> n >> k;
    D = 0;
    map<string, int> m;
    for(int i = 0; i < k; i++) {
        string s;
        cin >> s;
        m[s]++;
    }

    for(pair<string, int> p: m) {
        cnt[D] = p.second;

        for(int i = 0; i < n; i++) {
            letter[D][i] = p.first[i] - 'A';
        }
        D++;
    }
    memset(pos_bitmask, 0, sizeof pos_bitmask);

    for(int i = 0; i < D; i++){
        for(int j = 0; j < n; j++) {
            pos_bitmask[j][letter[i][j]] |= (1 << i);
        }
    }

    int mask[6];
    int full_bitmask = (1 << D) - 1;
    for(int j = 0; j < n; j++) {
        mask[j] = full_bitmask;
    }
    for(int i = 0; i < D; i++) {
        row_use[i] = 0;
    }

    rec(0, mask);
    cout << res << endl;
    return 0;
}