#include <cstdio>
#include <cmath>
#include <iostream>
#include <cstring>
#include <algorithm>
#include <queue>
#include <vector>
#include <map>
#include <unordered_map>
#include <set>
#define ll long long
#define fp(a,b,c) for(ll a=b;a<=c;a++)
#include <tuple>
#define fd(a,b,c) for(ll a=b;a>=c;a--)
#define pii pair<int,int>
#define pll pair<ll,ll>
#define fr first
#define sd second
#define mod 1000000007
#define inf 0x3f3f3f3f

//#define int long long

using namespace std;

const int maxN=100+10;
struct node{int to,flow,nex;};
	struct liu{
		int idx=1;
		int head[maxN*4],cur[maxN*4],dep[maxN*4],in[maxN*4],s,t,n,m;//起点，终点，点数，边数
		node g[maxN*100];
		int vis[maxN];
		inline void add(int u,int v,int flow){
			g[++idx]={v,flow,head[u]};
			head[u]=idx;
			g[++idx]={u,0,head[v]};
			head[v]=idx;
		}
		bool bfs(){
			queue<int>q;
			memset(in,0,sizeof(in));
			memset(dep,0x3f,sizeof(dep));
			q.push(s);
			dep[s]=1;
			in[s]=1;
			while(!q.empty()){
				int temp=q.front();
				q.pop();
				for(int i=head[temp];i;i=g[i].nex)
					if(!g[i].flow) continue;
				else if(dep[g[i].to]>dep[temp]+1){
					dep[g[i].to]=dep[temp]+1;
					if(!in[g[i].to])
						in[g[i].to]=1,q.push(g[i].to);
				}
			}
			return dep[t]!=0x3f3f3f3f;
		}
		inline int dfs(int now,int cap){
			if(now==t)return cap;
			int p=cap;
			for(int &i=cur[now];i;i=g[i].nex){
				if(!p) break;
				if(!g[i].flow&&dep[g[i].to]!=dep[now]+1) continue;
				int tp=dfs(g[i].to,min(p,g[i].flow));
				if(tp) g[i].flow-=tp,g[i^1].flow+=tp,p-=tp;
				else dep[g[i].to]=-1;
			}
            return cap-p;
		}
		inline int dinic(){
			int np=0,mf=0;
			while(bfs()){
				fp(i,1,n) cur[i]=head[i];
				while(np=dfs(s,inf)) mf+=np;
			}return mf;
		}
		inline void clear(){
			memset(in,0,sizeof(in));
			memset(dep,0,sizeof(dep));
			memset(cur,0,sizeof(cur));
			memset(head,0,sizeof(head));
			idx=1;
			s=0,t=0,n=0,m=0;
		}
	}mf;//求最大独立集

signed main(){
	cin >> mf.n >> mf.m >> mf.s >> mf.t;
	int u,v,w;
	for(int i=1;i<=mf.m;++i){
		cin >> u >> v >> w;
		mf.add(u,v,w);
	}
//	for(int i=1;i<=n;++i)
//		add(i,i+n,1);
//	for(int i=1;i<=m;++i){
//		cin >> u >> v;
//		add(u+n,v,inf),add(v+n,u,inf);
//	}	
//	s+=n;
	//cout << mf.idx << endl;
	cout <<mf.dinic() << endl;;
	
	return 0;
} 

结构体里的代码是之前的板子，应该没有较大的问题