[SHOI2007] 善意的投票

#include<cstdio>
#include<cstring>
#include<algorithm>
using namespace std;
int h[705],cur[705],n,m,dep[705],q[705],tot = 1,S,T;

struct edge{
	int to,nxt,z;
}e[2000005];
void add(int x,int y,int z)
{
	e[++tot] = edge{y,h[x],z},h[x] = tot;
	e[++tot] = edge{x,h[y],0},h[y] = tot;
}
int bfs()
{
	for (int i = 1; i <= T; i++) cur[i] = h[i];
	memset(dep,0,sizeof dep);
	int head = 0,tail = 1;
	q[1] = S,dep[S] = 1;
	while (head < tail)
	{
		int u = q[++head];
		for (int i = h[u]; i; i = e[i].nxt)
		{
			int v = e[i].to;
			if (dep[v] || e[i].z <= 0) continue;
			dep[v] = dep[u] + 1,q[++tail] = v;
		}
	}
	return dep[T];
}
int dinic(int u,int mn,int fa)
{
	if (u == T || mn <= 0) return mn;
	int flow = 0,sum = 0;
	for (int &i = cur[u]; i; i = e[i].nxt)
	{
		int v = e[i].to;
		if (dep[v] != dep[u] + 1 || v == fa || e[i].z <= 0) continue;
		sum = dinic(v,min(mn,e[i].z),u);
		if (sum <= 0) continue;
		flow += sum,mn -= sum,e[i].z -= sum,e[i ^ 1].z += sum;
		if (mn <= 0) break;
	}
	return flow;
}
int main()
{
	scanf("%d%d",&n,&m);
	S = n + 1,T = S + 1;
	for (int i = 1,q1; i <= n; i++) 
	{
		scanf("%d",&q1);
		if (q1) add(S,i,1); else add(i,T,1);
	}
	for (int i = 1,q1,p; i <= m; i++) scanf("%d%d",&q1,&p),add(q1,p,1),add(p,q1,1);
	int ans = 0;
	while (bfs()) ans += dinic(S,2147483647,S);
	printf("%d",ans);
}