#include<iostream> using namespace std; const int N = 20 +10; const int INF=0x3f3f3f; int ans,n; char a[N][N]; bool v[N]; void dfs(int step){ if(step == n + 1){ ans++; return; } for(int i = 1;i<=n;i++){ if(a[step][i] == '1' && !v[i]){ v[i] = 1; dfs(step+1); v[i] = 0; } } } int main(){ cin>>n; for(int i = 1;i<=n;i++){ for(int j = 1;j<=n;j++){ cin>>a[i][j]; } } dfs(1); cout<<ans; }