#include<iostream>
#include<cstring>
#include<cstdio>
#include<queue>

using namespace std;
int n, m, sorce, target, cnt;
int heads[10010], level[10010];
struct Node{
	int from;
	int to;
	int capacity;
	int next;
};
Node edges[100010];

void add(int f, int t, int c){
	edges[cnt].from=f;
	edges[cnt].to=t;
	edges[cnt].capacity=c;
	edges[cnt].next=heads[f];
	heads[f]=cnt;
	swap(f, t); cnt++;
	edges[cnt].from=f;
	edges[cnt].to=t;
	edges[cnt].capacity=0;
	edges[cnt].next=heads[f];
	heads[f]=cnt; cnt++;
	return;
}

bool bfs(){
	memset(level, -1, sizeof(level));
	queue<int> q;
	q.push(sorce);
	level[sorce]=0;
	while(!q.empty()){
		int top=q.front(); q.pop();
//		cout << top << endl;
		if(top==target) return true;
		for(int i=heads[top];i!=-1;i=edges[i].next){
			int t=edges[i].to;
			int c=edges[i].capacity;
//			printf("edges[%d]: from=%d, to=%d, capacity=%d, next=%d\n", i, edges[i].from, t, c, edges[i].next);
			if(level[t]==-1 && c>0){
				level[t]=level[top]+1;
				q.push(t);
			}
		}
	}
	return false;
}

int dfs(int u, int mx){
//	cout << u << endl;
	if(u==target || mx<=0) return mx;
	int sum=0;
	for(int i=heads[u];i!=-1;i=edges[i].next){
		int t=edges[i].to;
		int c=edges[i].capacity;
//		cout << t << endl;
		if(level[t]==level[u]+1 && c>0){
			int ans=dfs(t, min(mx-sum, c));
			sum+=ans;
			edges[i].capacity-=ans;
			edges[i^1].capacity+=ans;
			if(sum==mx) return mx;
		}
	}
	return sum;
}

int dinic(){
	int ans=0;
	while(bfs()){
//		printf("1 ");
		ans+=dfs(sorce, 0x3f3f3f3f);
//		printf("\n\n\n\n\n\n");
	}
//	printf("\n");
	return ans;
}

int main(){
	scanf("%d%d%d%d", &n, &m, &sorce, &target);
	memset(heads, -1, sizeof(heads));
	for(int i=0;i<m;i++){
		int f, t, c;
		scanf("%d%d%d", &f, &t, &c);
		add(f, t, c);
	}
	printf("%d\n", dinic());
	return 0;
}