#include <cstdio>

#include <iostream>

#define LL long long

#define maxn 10005

#define maxm 100005

using namespace std;

struct EdgeType {

    LL v,e,f;

};

struct EdgeType edge[maxn<<];

LL if_z,n,m,s,t,cnt=,head[maxn],deep[maxn];

LL que[maxn<<],h,tail,ans;

char Cget;

inline void in(LL &now)

{

    now=,if_z,Cget=getchar();

    while(Cget>''||Cget<'')

    {

        if(Cget=='-') if_z=-;

        Cget=getchar();

    }

    while(Cget>=''&&Cget<='')

    {

        now=now*+Cget-'';

        Cget=getchar();

    }

}

bool BFS()

{

    for(LL i=;i<=n;i++) deep[i]=-;

    h=,tail=,deep[s]=,que[h]=s;

    while(h<tail)

    {

        for(LL i=head[que[h]];i;i=edge[i].e)

            if(deep[edge[i].v]<&&edge[i].f)

            {

                deep[edge[i].v]=deep[que[h]]+;

                if(edge[i].v==t) return true;

                que[tail++]=edge[i].v;

            }

        h++;

    }

    return false;

}

LL flowing(LL now,LL flow)

{

    if(now==t||!flow) return flow;

    LL oldflow=;

    for(LL i=head[now];i;i=edge[i].e)

    {

        if(edge[i].f<=||deep[edge[i].v]!=deep[now]+) continue;

        LL pos=flowing(edge[i].v,min(flow,edge[i].f));

        flow-=pos;

        oldflow+=pos;

        edge[i].f-=pos;

        edge[i^].f+=pos;

        if(flow==) return oldflow;

    }

    if(oldflow==) deep[now]=-;

    return oldflow;

}

int main()

{

    in(n),in(m),in(s),in(t);

    LL u,v,w;

    while(m--)

    {

        in(u),in(v),in(w);

        edge[++cnt].v=v,edge[cnt].f=w,edge[cnt].e=head[u],head[u]=cnt;

        edge[++cnt].v=u,edge[cnt].f=,edge[cnt].e=head[v],head[v]=cnt;

    }

    while(BFS()) ans+=flowing(s,0x7fffffff);

    cout<<ans;

    return ;

}