#include <bits/stdc++.h>

using namespace std;

int n, m, s, t, cnt;

int l, r;

struct node {

    int to, nex, val;

}E[200005];

int head[100005];

int vis[10005];

int que[10005];

struct no1 {

    int to, edge;

}pre[10005];

bool bfs() {

    for(int i = 1; i <= r; i++) {

        vis[que[i]] = 0;

        pre[i].to = -1;

        pre[i].edge = -1;

    }

    l = 1, r = 0;

    vis[s] = 1;

    que[++r] = s;

    while(l <= r) {

        int u = que[l];

        l++;

        for(int i = head[u]; i; i = E[i].nex) {

            int v = E[i].to;

            if(!vis[v] && E[i].val > 0) {

                pre[v].to = u;

                pre[v].edge = i;

                if(v == t) return true;

                vis[v] = 1;

                que[++r] = v;

            }

        }

    }

    return false;

}

int EK() {

    int res = 0;

    while(bfs()) {

        int mi = 1e9;

        for(int i = t; i != s; i = pre[i].to) {

            mi = min(mi, E[pre[i].edge].val);

        }

        for(int i = t; i != s; i = pre[i].to) {

            E[pre[i].edge].val -= mi;

            E[pre[i].edge ^ 1].val += mi;

        }

        res += mi;

    }

    return res;

}

int main() {

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

    cnt = 1;

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

        int a, b, c;

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

        E[++cnt].to = b; E[cnt].nex = head[a]; E[cnt].val = c; head[a] = cnt;

        E[++cnt].to = a; E[cnt].nex = head[b]; E[cnt].val = 0; head[b] = cnt;

    }

    printf("%d\n", EK());

    return 0;

}

#include <bits/stdc++.h>

using namespace std;

int n, m, s, t, cnt;

int maxflow;

struct node {

    int to, nex, val;

}E[200005];

int head[10005];

int cur[10005];

int dep[10005];

int inque[10005];

bool bfs() {

    for(int i = 1; i <= n; i++) cur[i] = head[i], dep[i] = 0x3f3f3f3f, inque[i] = 0;

    dep[s] = 0;

    queue<int> que;

    que.push(s);

    inque[s] = 1;

    while(!que.empty()) {

        int u = que.front();

        que.pop();

        inque[u] = 0;

        for(int i = head[u]; i; i = E[i].nex) {

            int v = E[i].to;

            if(E[i].val > 0 && dep[v] > dep[u] + 1) {

                dep[v] = dep[u] + 1;

                if(!inque[v]) {

                    inque[v] = 1;

                    que.push(v);

                }

            }

        }

    }

    if(dep[t] != 0x3f3f3f3f) return true;

    else return false;

}

int vis;

int dfs(int x, int flow) {

    int rlow = 0;

    if(x == t) {

        vis = 1;

        maxflow += flow;

        return flow;

    }

    int used = 0; //当前使用了多少

    for(int i = cur[x]; i; i = E[i].nex) {

        cur[x] = i;  //更新弧

        int v = E[i].to;

        if(E[i].val > 0 && dep[v] == dep[x] + 1) {

            if(rlow = dfs(v, min(flow - used, E[i].val))) {

                used += rlow;

                E[i].val -= rlow;

                E[i ^ 1].val += rlow;

                if(used == flow) break; //用完了

            }

        }

    }

    return used;

}

void dinic() {

    int lowflow;

    while(bfs()) {

        vis = 1;

        while(vis) {

            vis = 0;

            dfs(s, 1000000000);

        }

    }

}

int main() {

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

    cnt = 1;

    maxflow = 0;

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

        int a, b, c;

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

        E[++cnt].to = b; E[cnt].nex = head[a]; E[cnt].val = c; head[a] = cnt;

        E[++cnt].to = a; E[cnt].nex = head[b]; E[cnt].val = 0; head[b] = cnt;

    }

    dinic();

    printf("%d\n", maxflow);

    return 0;

}