#include <stdio.h>
using namespace std;
int poz[27][27];
int dp[1000][30];
int N, M, i, j;
char x, y;
int main(){
    freopen("nrcuv.in", "r", stdin);
    freopen("nrcuv.out", "w", stdout);
    scanf("%d%d\n", &N, &M);
    for(i = 1; i <= M; i++){
        scanf("%c %c\n", &x, &y);
        poz[x-'a' + 1][y-'a' + 1] = 1;
    }
    for(i = 1; i <= ('z' - 'a' + 1); i++){
        dp[1][i] = 1;
    }
    for(i = 2; i <= N; i++){
        for(j = 1; j <= ('z' - 'a' + 1); j++){
            dp[i][j] = dp[i - 1][j] + 26 - poz[j][0];
        }
    }
    int rez = 0;
    for(i = 1; i <= ('z' - 'a' + 1); i++){
        rez += dp[N][i];
    }
    printf("%d", rez);
}