#include <bits/stdc++.h>
using namespace std;
#define INF 0x7ffffff
const int M = 1000005;
struct E{
int nxt,v,w;
};
E edge[M];
int dpth[M],head[M],cnt;
int n,m,s,t;
void add(int u,int v,int w){
cnt++;
edge[cnt].v = v;
edge[cnt].w = w;
edge[cnt].nxt = head[u];
head[u] = cnt;
}
//初始化从0开始存边 i^1是i的反向边
void init(){
cnt=-1;
memset(head,-1,sizeof(head));
}
//初始化分层图
bool bfs(){
memset(dpth,0,sizeof(dpth));
queue<int> q; q.push(s); dpth[s] = 1;
while(!q.empty()){
int u = q.front(); q.pop();
for(int v,i=head[u];i!=-1;i=edge[i].nxt){
{
v = edge[i].v;
if(edge[i].w>0&&dpth[v]==0){
dpth[v] = dpth[u]+1;
q.push(v);
}
}
}
}
if(dpth[t]!=0)
return true;
else return false;
}
int dfs(int u,int dist){
if(u==t)
return dist;
for(int v,i=head[u];i!=-1;i=edge[i].nxt){
v = edge[i].v;
if((dpth[v]==dpth[u]+1)&&edge[i].w!=0)
{
int di = dfs(v,min(dist,edge[i].w));
if(di>0){
edge[i].w-=di;
edge[i^1].w+=di;
return di;
}
}
}
return 0;
}
int dinic(){
int ans=0;
while(bfs())
while(int di = dfs(s,INF))
ans+=di;
return ans;
}
int main(){
cin>>n>>m>>s>>t;
init();
for(int i=1;i<=m;i++){
int x,y,z;
cin>>x>>y>>z;
add(x,y,z);
add(y,x,0);
}
cout<<dinic();
return 0;
}