#include <bits/stdc++.h>

using namespace std;

int D[26][1000], a[26][26];

int main(void) {
    ifstream cin("nrcuv.in");
    ofstream cout("nrcuv.out");
    
    int n, m, s = 0; char i, j;
    cin >> n >> m;
    
    while (m--) {
        cin >> i >> j;
        a[i - 'a'][j - 'a'] = a[j - 'a'][i - 'a'] = 1;
    }
    
    for (int i = 0; i < 26; i++)
        D[i][0] = 1;
        
    for (int i = 1; i < n; i++)
        for (int j = 0; j < 26; j++)
            for (int k = 0; k < 26; k++)
                if (!a[j][k])
                    D[j][i] += D[k][i - 1];
                    
    for (int i = 0; i < 26; i++)
        s += D[i][n - 1];
        
    cout << s;

    return 0;
}