rt,按着《算法竞赛进阶指南》打的，感觉一模一样QAQ

#include <bits/stdc++.h>
#define int long long
using namespace std;
const int inf = 1 << 31, N = 205, M = 10005;

int head[N], ver[M], edge[M], Next[M], d[N], /*当前弧优化*/now[M];
int n, m, s, t, tot, maxflow;
queue <int> q;

void add(int x, int y, int z) {
	ver[++tot] = y, edge[tot] = z, Next[tot] = head[x], head[x] = tot;
	ver[++tot] = x, edge[tot] = 0, Next[tot] = head[y], head[y] = tot;
}

bool bfs() { // 在残量网络上构造分层图 
	memset(d, 0, sizeof(d));
	while (q.size()) q.pop();
	q.push(s); d[s] = 1; now[s] = head[s];
	while (q.size()) {
		int x = q.front(); q.pop();
		for (int i = head[x]; i; i = Next[i])
			if (edge[i] && !d[ver[i]]) {
				q.push(ver[i]);
				now[ver[i]] = head[ver[i]];
				d[ver[i]] = d[x] + 1;
				if (ver[i] == t) return 1;
			}
	}
	return 0; 
}

int dinic(int x, int flow) { // 在当前分层图上增广 
	if (x == t) return flow;
	int rest = flow, k, i;
	for (i = now[x]; i && rest; i = Next[i]) {
		now[x] = i; // 当前弧优化（避免重复遍历从 x 出发不可扩展的边） 
		if (edge[i] && d[ver[i]] == d[x] + 1) {
			k = dinic(ver[i], min(rest, edge[i]));
			if (!k) d[ver[i]] = 0; // 剪枝，去掉增广完毕的点
			edge[i] -= k;
			edge[i ^ 1] += k; 
			rest -= k;
		}
	}
	return flow - rest;
}

signed main() {
	cin >> n >> m >> s >> t;
	tot = 1;
	for (int i = 1; i <= m; i++) {
		int x, y, c; cin >> x >> y >> c;
		add(x, y, c);
	}
	int flow = 0;
	while (bfs())
		while (flow = dinic(s, inf)) maxflow += flow;
	cout << maxflow;
}