#include <bits/stdc++.h>
using namespace std;
typedef long long ll;


const int mod = 1e9+7;


string s[110];

vector <pair<int, int> > g;

int rem[1010][1010];


queue <pair<int, int> > q;

struct matr{
    ll a[1010][1010];
    void clr(){
        for (int i = 0; i <= k; i++)
            for (int j = 0; j <= k; j++)
                a[i][j] = 0;
    }
};

int k;

matr operator * (matr fi, matr se){
    matr th;
    th.clr();
    for (int i = 0; i <= k; i++){
        for (int j = 0; j <= k; j++){
            for (int l = 0; l <= k; l++){
                th.a[i][j] = (th.a[i][j] + fi.a[i][l] * se.a[l][j])%mod;
            }
        }
    }
    return th;
}

matr binpow(matr x, ll y){
    matr ans = x;
    --y;
    while(y){
        if (y & 1)
            ans = ans * x;
        y>>=1;
        x = x * x;
    }
    return ans;
}

int main(){
    ios_base::sync_with_stdio(0);cin.tie(0);
    int n, qq;
    cin >> n >> qq;
    for (int i = 1; i <= qq; i++){
        int sz;
        cin >> sz;
        cin >> s[i];
    }

    k = 1;
    g.push_back({0, 0});
    rem[0][0] = 1;
    q.push({0, 0});

    matr aa;
    aa.clr();

    while(!q.empty()){
        int pos = q.front().first, len = q.front().second;
        q.pop();
        string scp = s[pos].substr(0, len);
        for (char c = 'a'; c <= 'z'; c++){
            string ss = scp + c;
            int nxtpos = -1, nxtlen = -1;
            bool flag = 1;
            for (int i = 1; i <= qq; i++){
                if (s[i] == ss){
                    flag = 0;
                    break;
                }
            }
            if (flag == 0)
                continue;
            while(!ss.empty()){
                int sz = ss.size();
                for (int l = 1; l <= qq; l++){
                    if (s[l].substr(0, sz) == ss){
                        nxtpos = l;
                        nxtlen = sz;
                        break;
                    }
                }
                if (nxtpos != -1)
                    break;
                ss.erase(0, 1);
            }
            if (nxtpos == -1){
                ++aa.a[rem[pos][len]][1];
            } else {
                if (rem[nxtpos][nxtlen] == 0){
                    rem[nxtpos][nxtlen] = ++k;
                    g.push_back({nxtpos, nxtlen});
                    q.push({nxtpos, nxtlen});
                }
                ++aa.a[rem[pos][len]][rem[nxtpos][nxtlen]];
            }
        }
    }
    if (k > 102)
        assert(0);
    matr ansm = binpow(aa, n);
    ll ans = 0;
    for (int i = 1; i <= k; i++){
        ans = (ans + ansm.a[1][i])%mod;
    }
    cout << ans;




}