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

typedef pair<int,int>   II;
typedef vector< II >      VII;
typedef vector<int>     VI;
typedef vector< VI >     VVI;
typedef long long int     LL;
typedef unsigned long long int ULL;

#define PB push_back
#define MP make_pair
#define F first
#define S second
#define SZ(a) (int)(a.size())
#define ALL(a) a.begin(),a.end()
#define SET(a,b) memset(a,b,sizeof(a))
#define LET(x,a) __typeof(a) x(a)

#define rep(i, begin, end) for (__typeof(end) i = (begin) - ((begin) > (end)); i != (end) - ((begin) > (end)); i += 1 - 2 * ((begin) > (end)))
//Works for forward as well as backward iteration

#define gu getchar
#define pu putchar
#define si(n) scanf("%d",&n)
#define dout(n) printf("%d\n",n)
#define sll(n) scanf("%lld",&n)
#define lldout(n) printf("%lld\n",n)

#define DRT() int t; si(t); while(t--)

#define PlUSWRAP(index,n) index = (index+1)%n        //index++; if(index>=n) index=0
#define MINUSWRAP(index,n) index = (index + n -1)%n     //index--; if(index<0) index=n-1
#define ROUNDOFFINT(d) d = (int)((double)d + 0.5)    //Round off d to nearest integer

#define FLUSHN while(gu()!='\n')
#define FLUSHS while(gu()!=' ')

#define TRACE

#ifdef TRACE
#define trace1(x)                cerr << #x << ": " << x << endl;
#define trace2(x, y)             cerr << #x << ": " << x << " | " << #y << ": " << y << endl;
#define trace3(x, y, z)          cerr << #x << ": " << x << " | " << #y << ": " << y << " | " << #z << ": " << z << endl;
#define trace4(a, b, c, d)       cerr << #a << ": " << a << " | " << #b << ": " << b << " | " << #c << ": " << c << " | " << #d << ": " << d << endl;
#define trace5(a, b, c, d, e)    cerr << #a << ": " << a << " | " << #b << ": " << b << " | " << #c << ": " << c << " | " << #d << ": " << d << " | " << #e << ": " << e << endl;
#define trace6(a, b, c, d, e, f) cerr << #a << ": " << a << " | " << #b << ": " << b << " | " << #c << ": " << c << " | " << #d << ": " << d << " | " << #e << ": " << e << " | " << #f << ": " << f << endl;

#else

#define trace1(x)
#define trace2(x, y)
#define trace3(x, y, z)
#define trace4(a, b, c, d)
#define trace5(a, b, c, d, e)
#define trace6(a, b, c, d, e, f)

#endif

#define off ios_base::sync_with_stdio(0); cin.tie(0); cout.tie(0)
int n;
const int N = 22;
int arr[22][22];
int dp[1<<N];
int mod = 1e9+7;
int main() {
    scanf("%d",&n);
    rep(i,0,n)
    {
        rep(j,0,n)
        scanf("%d",&arr[i][j]);
    }
    // dp[mask] stores the number of ways to make the subset of the women 
    // represented by the mask to get married to the choosing from the 
    // first 'a' men, where 'a' is the number of set bits in the mask.  
    dp[0] = 1;
    rep(mask,0,(1<<n)-1)
    {
        int a = __builtin_popcount(mask);
        // loop over all the women, to see if we can find someone who is not paired still.
        rep(i,0,n)
        {
          	// checking if the 'a'th man can be paired up with the ith woman 
          	// and that woman has not been paired up with anyone else yet.
            if(arr[a][i] && !(mask&(1<<i)))
            {
                int m = mask^(1<<i);
                dp[m] = (dp[m]+dp[mask])%mod;
            }
        }
    }
    printf("%d\n",dp[(1<<n)-1]);
    return 0;
}

Measured memory_bytes: 10496