#include<bits/stdc++.h>

using namespace std;

const long long MAXN = ;//点数的最大值

const long long MAXM = ;//边数的最大值

const long long INF = 1e15 + ;

struct Edge

{

    long long to,next,cap,flow;

} edge[MAXM]; //注意是MAXM

long long tol;

long long head[MAXN];

long long gap[MAXN],dep[MAXN],cur[MAXN];

long long n, m, s, t;

void init()

{

    tol = ;

    memset(head,-,sizeof(head));

}

void addedge(long long u,long long v,long long w,long long rw = )

{

    edge[tol].to = v;

    edge[tol].cap = w;

    edge[tol].flow = ;

    edge[tol].next = head[u];

    head[u] = tol++;

    edge[tol].to = u;

    edge[tol].cap = rw;

    edge[tol].flow = ;

    edge[tol].next = head[v];

    head[v] = tol++;

}

long long Q[MAXN];

void BFS(long long start,long long end)

{

    memset(dep,-,sizeof(dep));

    memset(gap,,sizeof(gap));

    gap[] = ;

    long long front = , rear = ;

    dep[end] = ;

    Q[rear++] = end;

    while(front != rear)

    {

        long long u = Q[front++];

        for(long long i = head[u]; i != -; i = edge[i].next)

        {

            long long v = edge[i].to;

            if(dep[v] != -)

                continue;

            Q[rear++] = v;

            dep[v] = dep[u] + ;

            gap[dep[v]]++;

        }

    }

}

long long S[MAXN];

long long sap(long long start,long long end,long long N)

{

    BFS(start,end);

    memcpy(cur,head,sizeof(head));

    long long top = ;

    long long u = start;

    long long ans = ;

    while(dep[start] < N)

    {

        if(u == end)

        {

            long long Min = INF;

            long long inser;

            for(long long i = ; i < top; i++)

                if(Min > edge[S[i]].cap - edge[S[i]].flow)

                {

                    Min = edge[S[i]].cap - edge[S[i]].flow;

                    inser = i;

                }

            for(long long i = ; i < top; i++)

            {

                edge[S[i]].flow += Min;

                edge[S[i]^].flow -= Min;

            }

            ans += Min;

            top = inser;

            u = edge[S[top]^].to;

            continue;

        }

        bool flag = false;

        long long v;

        for(long long i = cur[u]; i != -; i = edge[i].next)

        {

            v = edge[i].to;

            if(edge[i].cap - edge[i].flow && dep[v]+ == dep[u])

            {

                flag = true;

                cur[u] = i;

                break;

            }

        }

        if(flag)

        {

            S[top++] = cur[u];

            u = v;

            continue;

        }

        long long Min = N;

        for(long long i = head[u]; i != -; i = edge[i].next)

            if(edge[i].cap - edge[i].flow && dep[edge[i].to] < Min)

            {

                Min = dep[edge[i].to];

                cur[u] = i;

            }

        gap[dep[u]]--;

        if(!gap[dep[u]])

            return ans;

        dep[u] = Min + ;

        gap[dep[u]]++;

        if(u != start)

            u = edge[S[--top]^].to;

    }

    return ans;

}

int main(){

    init();

    scanf("%lld %lld %lld %lld", &n , &m, &s, &t);

    for(long long i = ; i < m; i++){

        long long u, v, w;

        scanf("%lld %lld %lld", &u, &v, &w);

        addedge(u,v,w);

    }

    printf("%lld\n", sap(s,t,n));

}