KM板題：

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

inline void read(int &num)
{
	char ch; num = 0; int flag = 1;
	while((ch=getchar()) < '0' || ch > '9')if(ch == '-') flag = -flag;
	while(ch >= '0' && ch <= '9') num = num*10 + ch-'0', ch = getchar();
	num *= flag;
}
const int MAXN = 25;
int n, m, w[MAXN][MAXN], x, cy[MAXN], dbx[MAXN], dby[MAXN], pre[MAXN], slk[MAXN];
bool vis[MAXN];
void bfs(int now)
{
	memset(vis, 0, sizeof vis);
	memset(slk, 0x3f, sizeof slk);
	int x, y = 0, Minloc;
	cy[y] = now;
	do {
		x = cy[y]; vis[y] = 1; Minloc = 0;
		for(int i = 1; i <= n; i++) if(!vis[i])
		{
			if(dbx[x]+dby[i]-w[x][i] < slk[i]) slk[i] = dbx[x]+dby[i]-w[x][i], pre[i] = y;
			if(slk[i] < slk[Minloc]) Minloc = i;
		}
		for(int i = 0, inc = slk[Minloc]; i <= n; i++)
			if(vis[i]) dbx[cy[i]] -= inc, dby[i] += inc;
			else slk[i] -= inc;
		y = Minloc;
	}while(~cy[y]);
	while(y) cy[y] = cy[pre[y]], y = pre[y];
}

int KM()
{
	memset(cy, -1, sizeof cy);
	for(int i = 1; i <= n; i++) bfs(i);
	int ret = 0;
	for(int i = 1; i <= n; i++) ret += w[cy[i]][i];
	return ret;
}

int main()
{
	read(n);
	for(int i = 1; i <= n; ++i)
		for(int j = 1; j <= n; ++j)
			read(w[i][j]);
	for(int i = 1, x; i <= n; ++i)
		for(int j = 1; j <= n ; ++j)
			read(x), w[j][i] *= x;
	printf("%d\n", KM());
}