#include<bits/stdc++.h>
using namespace std;
const int INF=0x3f3f3f3f;
const int maxn=1e5+5;
int n,m,s,t;
struct edges
{
    int to,f,next;
}edge[maxn<<1];
int head[maxn],gap[maxn],d[maxn],pre[maxn],last[maxn],cnt;
void add(int from,int to,int f)
{
    edge[cnt].to=to;
    edge[cnt].f=f;
    edge[cnt].next=head[from];
    head[from]=cnt++;
}
void bfs(void)
{
    memset(d,-1,sizeof(d));
    d[t]=0;
    gap[0]++;
    queue<int>q;
    q.push(t);
    while(q.size()){
        int tmp=q.front();q.pop();
        for(int i=head[tmp];~i;i=edge[i].next){
            int to=edge[i].to;
            if(d[to]==-1&&edge[i].f){
                d[to]=d[tmp]+1;
                gap[d[to]]++;
                q.push(to);
            }
        }
    }
}
int max_flow(void)
{
    bfs();
    int flow=0;
    int x=s;
    for(int i=1;i<=n;i++) last[i]=head[i];
    while(d[s]<n){
        if(x==t){
            int neck=0,tmp=INF;
            for(int i=s;i!=t;i=edge[last[i]].to){
                if(tmp>edge[last[i]].f){
                    tmp=edge[last[i]].f;neck=i;
                }
            }
            for(int i=s;i!=t;i=edge[last[i]].to){
                edge[last[i]].f-=tmp;
                edge[last[i]^1].f+=tmp;
            }
            flow+=tmp;x=neck;
        }
        int i;
        for(i=last[x];~i;i=edge[i].next)
            if(d[x]==d[edge[i].to]+1&&edge[i].f)break;
        if(i!=-1){
            last[x]=i;
            pre[edge[i].to]=x;
            x=edge[i].to;
        }else{
            int minl=INF;
            if(!--gap[d[x]]) break;
            last[x]=head[x];
            for(int i=head[x];~i;i=edge[i].next){
                if(minl>d[edge[i].to]&&edge[i].f) minl=d[edge[i].to];
            }
            d[x]=minl+1;
            gap[d[x]]++;
            if(x!=s) x=pre[x];
        }
    }
    return flow;
}
int main(void)
{
    memset(head,-1,sizeof(head));
    cin>>n>>m>>s>>t;
    int x,y,z;
    for(int i=1;i<=m;i++){
        cin>>x>>y>>z;
        add(x,y,z);add(y,x,0);
    }
    cout<<max_flow()<<endl;
}