#include<bits/stdc++.h>
#define int long long
using namespace std;
const int N=105;
const int M=1e4+5;
const int inf=1e18;

static char buf[1000000],*p1=buf,*p2=buf;
#define getchar() p1==p2&&(p2=(p1=buf)+fread(buf,1,1000000,stdin),p1==p2)?EOF:*p1++
inline int wrd(){int x=0,f=1;char c=getchar();while(c<'0' || c>'9'){if(c=='-') f=-1;c=getchar();}while(c>='0' && c<='9') {x=(x<<3)+(x<<1)+c-48;c=getchar();}return x*f;}
inline void write(int x){static char buf[20];static int len=-1;if(x<0)putchar('-'),x=-x;do buf[++len]=x%10,x/=10;while(x);while(len>=0)putchar(buf[len--]+48);}

int n,m,s,t,as,cnt=1,head[N];
struct edge{int to,w,nxt;}e[M];
void add(int u,int v,int w){e[++cnt]={v,w,head[u]},head[u]=cnt;}
void addedge(int u,int v,int w){add(u,v,w),add(v,u,0);}

bool vs[N];
int dep[N],cur[N];

bool bfs(){
	queue<int> q;
	for(int i=1;i<=n;++i) vs[i]=0,dep[i]=inf;
	q.push(s),dep[s]=0,cur[s]=head[s];
	while(q.size()){
		int u=q.front(); q.pop();
		for(int i=head[u];i;i=e[i].nxt){
			int v=e[i].to;
			if(dep[v]!=inf || !e[i].w) continue;
			dep[v]=dep[u]+1,cur[v]=head[v],q.push(v);
		}
	}
	return dep[t]!=inf;
}
int dfs(int u,int flow){
	if(u==t) return flow;
	int as(0);
	for(int i=cur[u];i&&flow;i=e[i].nxt){
		cur[u]=i;
		int v=e[i].to;
		if(dep[v]!=dep[u]+1 || !e[i].w) continue;
		int x=dfs(v,min(flow,e[i].w));
		if(!x) dep[v]=inf;
		else as+=x,flow-=x,e[i].w-=x,e[i^1].w+=x;
	}
	return as;
}

signed main(){
	n=wrd(),m=wrd(),s=wrd(),t=wrd();
	for(int i=1;i<=m;++i){
		int u=wrd(),v=wrd(),w=wrd();
		addedge(u,v,w);
	}
	while(bfs()) as+=dfs(s,inf);
	write(as);
}