#include<stdio.h>
#include<string.h>
#include<stdlib.h>
#include<algorithm>
#include<vector>
#include<string>
#include<set>
#include<memory.h>
#include<map>
#include<assert.h>
#include<time.h>

const int N_ = 3005;
const int MOD = 1000000007;
typedef long long lld;
int N;
char *A[N_];
char D[N_][N_];
lld fac[N_] = {1,};

bool cmp(const char*a, const char*b){
    return strcmp(a, b) < 0;
}

lld GetResult(int left, int right, int depth){
    int i, cnt = 0, last_right = left - 1; lld ret = 1;

    for(i = left; i <= right; i++){
        if(i == right || A[i][depth] != A[i+1][depth]){
            if(A[i][depth] != 0) ret = (ret * GetResult(last_right + 1, i, depth + 1)) % MOD;
            ++cnt; last_right = i;
        }
    }

    ret = (ret * fac[cnt]) % MOD;
    return ret;
}

int main(){
    int i, j;

    scanf("%d",&N);
    for(i = 1; i <= N; i++){
        scanf("%s",D[i]); A[i] = D[i];
        fac[i] = (fac[i-1] * i) % MOD;
    }

    std::sort(A+1, A+N+1, cmp);

    printf("%lld\n",GetResult(1, N, 0));
    return 0;
}