hdu6026

#include<cstdio>
#include<iostream>
#include<cstring>
#include<algorithm>
using namespace std;
typedef long long ll;
const int maxn = 60;
const int INF = 0x3f3f3f3f;
const int MOD = 1e9 +7;
int d[maxn];
char s[maxn][maxn];
int dis[maxn][maxn];
int n;

void Dijkstra()
{
    fill(d, d + n, INF);
    d[0] = 0;
    for(int  i = 0; i < n; i++)
    {
        int minn = INF, u = -1;
        for(int j = 0; j < n; j++)
        {
            if(d[j] < minn)
            {
                minn = d[j];
                u = j;
            }
        }
        if(u == -1) break;

        for(int j = 0; j < n; j++)
        {
            if(d[u] + dis[u][j] < d[j])
                d[j] = d[u] + dis[u][j];
        }
    }
}

int main()
{
    while(cin >> n)
    {
        for(int i = 0; i < n; i++)
        {
            scanf("%s", s[i]);
            for(int j = 0; j < n; j++)
                dis[i][j] = s[i][j] - '0';
        }

        Dijkstra();
        ll ans = 1;
        ll cnt;
        for(int i = 1; i < n; i++)
        {
            cnt = 0;
            for(int j = 0; j < n; j++)
            {
                if(dis[j][i] && d[j] + dis[j][i] == d[i])
                    cnt++;
            }
            ans = ans * cnt % MOD;
        }
        cout << ans << endl;
    }
    return 0;
}