#include <bits/stdc++.h>
using namespace std;
#define PB push_back
#define ZERO (1e-10)
#define INF int(1e9+1)
#define CL(A,I) (memset(A,I,sizeof(A)))
#define DEB printf("DEB!\n");
#define D(X) cout<<"  "<<#X": "<<X<<endl;
#define EQ(A,B) (A+ZERO>B&&A-ZERO<B)
typedef long long ll;
typedef pair<ll,ll> pll;
typedef vector<int> vi;
typedef pair<int,int> ii;
typedef vector<ii> vii;
#define IN(n) int n;scanf("%d",&n);
#define FOR(i, m, n) for (int i(m); i < n; i++)
#define F(n) FOR(i,0,n)
#define FF(n) FOR(j,0,n)
#define FT(m, n) FOR(k, m, n)
#define aa first
#define bb second
void ga(int N,int *A){F(N)scanf("%d",A+i);}
#define MX (1024)
#define AL (26)
int g[MX][AL],f[MX],E,q[MX],O[MX];
void ini(){E=1;F(AL)g[0][i]=0;CL(f,0),CL(O,0);}
void add(char*s){
    int L=strlen(s),u=0,c;
    F(L){
        if(!g[u][c=s[i]-97]){
            g[u][c]=E++;
            F(AL)g[E-1][i]=0;
        }
        u=g[u][c];
    }
    O[u]=1;
}
void bld(){
    int x,r,b=-1,e=0,u;
    F(AL)if(g[0][i])f[g[0][i]]=0,q[e++]=g[0][i];
    while(++b<e)F(AL){
        x=g[u=q[b]][i],r=g[f[u]][i];
        if(!x)g[u][i]=r;
        else{
            q[e++]=x,f[x]=r;
//            for(auto&h:O[r])O[x].PB(h);
        }
    }
}
#define MOD 1000000007
char s[MX];
int L,N,Q,dp[MX][MX];
int dyn(int u,int l){
    if(O[u])return 0;
    if(l==N)return 1;
    int&v=dp[u][l];
    if(~v)return v;
    v=0;
    F(26)v=(v+dyn(g[u][i],l+1))%MOD;
    return v;
}
int main(void){
    scanf("%d%d",&N,&Q),CL(dp,-1),ini();
    F(Q){
        scanf("%*d%s",s);
        add(s);
    }
    bld();
    printf("%d\n",dyn(0,0));
    return 0;
}