莫名3个点WA，求教

#include <cstdio>
#include <algorithm>
#include <vector>
#include <cstring>
using namespace std;
char tc()
{
    static char fl[100000],*A=fl,*B=fl;
    return A==B&&(B=(A=fl)+fread(fl,1,100000,stdin),A==B)?EOF:*A++;
}
int read()
{
    char c;while(c=tc(),(c<'0'||c>'9')&&c!='-');
    int x=0,y=1;c=='-'?y=-1:x=c-'0';
    while(c=tc(),c>='0'&&c<='9')x=x*10+c-'0';
    return x*y;
}
const int MAXN=10005,MAXM=100005;
int N,M,S,T,x,y,c,ans;
int W[MAXM],To[MAXM],cnt;
int l[MAXM*5],h,t,dist[MAXN];
vector <int> a[MAXN];
bool BFS()
{
    h=t=0;
    l[++t]=S;
    memset(dist,0,sizeof(dist));dist[S]=1;
        while(h<t){
            int front=l[++h];
                for(int i=0;i<a[front].size();i++){
                    int to=a[front][i];
                    if(!dist[To[to]] && W[to]>0){
                        dist[To[to]]=dist[front]+1;
                        l[++t]=To[to];
                    }
                }
        }
    return dist[T]>0;
}
int find(int now,int x)
{
    if(now==T) return x;
        for(int i=0;i<a[now].size();i++){
            int to=a[now][i];
            if(dist[To[to]]==(dist[now]+1) && W[to]>0){
                int fd=find(To[to],min(x,W[to]));
                if(fd>0){
                    W[to]-=fd;
                    W[to^1]+=fd;
                    return fd;
                }
            }
        }
    return 0;
}
int main()
{
    freopen("x.txt","r",stdin);
    N=read(),M=read(),S=read(),T=read();
        for(int i=1;i<=M;i++){
             x=read(),y=read(),c=read();
             W[cnt]=c,To[cnt]=y;a[x].push_back(cnt);cnt++;
             W[cnt]=0,To[cnt]=x;a[y].push_back(cnt);cnt++;
        }
        while(BFS()){
            ans+=find(S,2e9);
        }
    printf("%d",ans);
    return 0;
}