#include <cstdio>

    #include <iostream>

    #include <cstring>

    #include<queue>

    using namespace std;

    const int INF = 0x3fffffff;

    int  g[1005][1005];

    bool vis[1005];

    int m;

    int Edmond_Karp(int s,int t)

    {

        int pre[1005];

        int flow[1005];

        memset(pre,0,sizeof(pre));

        for(int i=0;i<=m;i++)   flow[i] = INF;

        queue<int>q;

        q.push(s);

        while(q.size())

        {

            int v = q.front();

            q.pop();

            for(int i=1;i<=m;i++)

            {

                if(pre[i] || i==v || g[v][i]==0)  continue;

                pre[i] = v;

                flow[i] = min(flow[v],g[v][i]);

                if(i==t)

                {

                    for(int j=t;j!=s;j=pre[j])

                    {

                        g[pre[j]][j]-=flow[t];

                        g[j][pre[j]]+=flow[t];

                    }

                    return flow[t];

                }

                q.push(i);

            }

        }

         return 0;

    }

    int find_flows(int s,int t)

    {

        int f = 0;

        while(1)

        {

            memset(vis,0,sizeof(vis));

            int flow = Edmond_Karp(s,t);

            if(flow == 0)   return f;

            f+=flow;

        }

    }

    int main()

    {

        int a, b, len;

        int s, t, p;

            scanf("%d%d", &m, &p);

            scanf("%d%d",&s,&t);

            memset(g,0,sizeof(g));

            while(p--)

            {

                scanf("%d%d%d", &a, &b, &len);

                g[a][b] += len;

            }

            printf("%d\n", find_flows(s,t));

        return 0;

    }