1 #include<cstring>
 2 #include<cstdio>
 3 #include<iostream>
 4 #define min(a,b) ((a)<(b)?(a):(b))
 5 using namespace std;
 6 inline int rd(){
 7     int x=0,f=1;char c=getchar();
 8     while(c<'0'||c>'9'){if(c=='-')f=-1; c=getchar();}
 9     while(c>='0'&&c<='9'){x=x*10+c-'0'; c=getchar();}
10     return f*x;
11 }
12 const int maxn=(1e4)+50,maxm=(1e5)+50;
13 int num_edge=-1,edge_head[maxn],N,M,S,T,w,u,v,Q[maxn<<1],f1,f2,Dep[maxn],Cur[maxn];
14 struct Edge{int to,nx,dis;}edge[maxm<<1];
15 inline void Add_edge(int from,int to,int dis){
16     edge[++num_edge].nx=edge_head[from];
17     edge[num_edge].to=to;
18     edge[num_edge].dis=dis;
19     edge_head[from]=num_edge;
20     return;
21 }
22 inline bool Bfs(){
23     memset(Dep,0,sizeof(Dep));
24     Dep[S]=1;
25     f1=f2=1;
26     Q[f2++]=S;
27     while(f1<f2){
28         int x=Q[f1++];
29         for(int i=edge_head[x];i!=-1;i=edge[i].nx){
30             int y=edge[i].to;
31             if(edge[i].dis&&Dep[y]==0){
32                 Dep[y]=Dep[x]+1;
33                 Q[f2++]=y;
34             }
35         }
36     }
37     if(Dep[T])return 1;
38     return 0;
39 }
40 inline int Dfs(int x,int fw){
41     if(x==T)return fw;
42     for(int &i=Cur[x];i!=-1;i=edge[i].nx){
43         int y=edge[i].to;
44         if(Dep[y]==Dep[x]+1&&edge[i].dis){
45             int p=Dfs(y,min(fw,edge[i].dis));
46             if(p>0){
47                 edge[i].dis-=p;
48                 edge[i^1].dis+=p;
49                 return p;
50             }
51         }
52     }
53     return 0;
54 }
55 inline int Dinic(){
56     int ans=0;
57     while(Bfs()){
58         for(int i=1;i<=N;i++)Cur[i]=edge_head[i];
59         while(int k=Dfs(S,1<<30))ans+=k;
60     }
61     return ans;
62 }
63 int main(){
64     memset(edge_head,-1,sizeof(edge_head));
65     N=rd();M=rd();S=rd();T=rd();
66     for(int i=1;i<=M;i++){
67         u=rd();v=rd();w=rd();
68         Add_edge(u,v,w);
69         Add_edge(v,u,0);
70     }
71     printf("%d\n",Dinic());
72     return 0;
73 }