Rt，真不知道哪里错了，评测记录，求dalao帮忙

#include<iostream>
#include<cstdio>
#include<cmath>
#include<string>
#include<cstring>
#include<algorithm>
#include<queue>
#include<stack>
#include<vector>
#include<map>
#include<complex>
using namespace std;
inline int read(){
	int x=0,f=1;char ch=getchar();
	while(ch<'0'||ch>'9'){if(ch=='-')f=-1;ch=getchar();}
	while(ch>='0'&&ch<='9'){x=x*10+ch-'0';ch=getchar();}
	return x*f;
}
const int inf=2147483647;
int maxn,cost;
int top=1,head[5001];
int dis[5001];
int n,m,s,t,book[5001],c[21][21],d[21][21],e[21][21];
int xx[8]={-1,1,0,0,-1,-1,1,1};
int yy[8]={0,0,-1,1,1,-1,1,-1};
struct point{
    int v,w,val,next;
}a[100001];
struct b{
    int fa;
    int v;
}b[5001];
inline void _add(int u,int v,int val,int w){
    a[++top].v=v;
    a[top].val=val;
    a[top].w=w;
    a[top].next=head[u];
    head[u]=top;
}
inline void add(int u,int v,int val,int w){
	_add(u,v,val,w);
	_add(v,u,0,-w);
}
bool spfa(){
	queue<int> q;
    memset(b,0,sizeof(b));
    memset(book,0,sizeof(book));
    for(int i=0;i<=t;i++)
    	dis[i]=inf;
    dis[s]=0;
    q.push(s);
    book[s]=1;
    while(!q.empty()){
        int u=q.front();
        book[u]=0;
        q.pop();
        for(int i=head[u];i;i=a[i].next){
            int v=a[i].v,w=a[i].w;
            if(a[i].val>0&&dis[v]>dis[u]+w){
                dis[v]=dis[u]+w;
                b[v].fa=u,b[v].v=i;
                if(book[v]==0){
                    q.push(v);
                    book[v]=1;
                }
            }
        }
    }
    return dis[t]!=inf;
}
void EK(){
    while(spfa()){
        int minn=inf;
        for(int i=t;i!=s;i=b[i].fa)
			minn=min(minn,a[b[i].v].val);
        for(int i=t;i!=s;i=b[i].fa){
            a[b[i].v].val-=minn;
            a[b[i].v^1].val+=minn;
        }
        maxn+=minn;
        cost+=minn*dis[t];
    }
    return;
}
int p(int x,int y){
	return (x-1)*n+y;
}
int main()
{
    n=read(),m=read();
    s=0,t=n*m*2+1;
    int sum1=0,sum2=0,pd=0;
    for(int i=1;i<=n;i++)
    	for(int j=1;j<=m;j++){
    		char ch;
    		cin>>ch;
    		if(ch=='1'){
    			sum1++;
    			c[i][j]=1;
			}
		}
	for(int i=1;i<=n;i++)
    	for(int j=1;j<=m;j++){
    		char ch;
    		cin>>ch;
    		if(ch=='1'){
    			sum2++;
    			d[i][j]=1;
			}
		}
	if(sum1!=sum2){
		cout<<-1;
		return 0;
	}
	for(int i=1;i<=n;i++){
		for(int j=1;j<=m;j++){
			if(c[i][j]==1&&d[i][j]==0){
				pd++;
				add(s,p(i,j),1,0);
			}
			if(c[i][j]==0&&d[i][j]==1)
				add(p(i,j)+n*m,t,1,0);
		}
	}
	for(int i=1;i<=n;i++){
		for(int j=1;j<=m;j++){
			char ch;
			cin>>ch;
			int x=ch-'0';
			add(p(i,j),p(i,j)+n*m,x/2,0);
			if((c[i][j]^d[i][j])&&(x&1))
				add(p(i,j),p(i,j)+n*m,1,0);
			for(int k=0;k<8;k++){
				int tx=i+xx[k],ty=j+yy[k];
				if(tx<1||tx>n||ty<1||ty>m)
					continue;
				add(p(i,j)+n*m,p(tx,ty),inf,1);
			}
		}
	}
    EK();
    if(maxn!=pd){
    	cout<<-1;
    	return 0;
	}
    cout<<cost;
    return 0;
}