#include <iostream>
#include <algorithm>
#include <vector>
#include <queue>
#include <cstring>
const int maxn = 1214;
const long long INF = 1e10;

struct edge {
	int to;
	int cap;
	size_t rev;//反向边的编号
};


int cur[maxn];
int level[maxn];
bool isedge[maxn][maxn];
std::vector <edge> G[maxn];

void add_edge(int x, int y, int cap) {
	if (isedge[x][y]) {
		G[x][isedge[x][y]].cap += cap;
	}
	else {
		
		G[x].push_back(edge{ y,cap,G[y].size() });
		G[y].push_back(edge{ x,0,G[x].size() - 1 });
		isedge[x][y] = G[x].size()-1;
	}
}//邻接表存图，注意去掉重边

void find_level(int s,int t) {
	std::queue <int> q;
	q.push(s);
	memset(level, -1, sizeof(level));
	level[s] = 0;
	while (!q.empty()) {
		int head = q.front();
		q.pop();
		for (int i = 0; i < G[head].size(); ++i) {
			if (level[G[head][i].to] == -1 && G[head][i].cap > 0) {
				level[G[head][i].to] = level[head] + 1;
				q.push(G[head][i].to);
			}
		}
	}
}//生成分层图

int dfs(int s,int t,int f) {
	if (s == t)return f;
	for (int& i = cur[s]; i < G[s].size(); ++i) {
		edge& e = G[s][i];
		if (level[e.to] > level[s] && e.cap > 0) {
			int temp = dfs(e.to, t, std::min(f, e.cap));
			if (temp > 0) {
				e.cap -= temp;
				G[e.to][e.rev].cap += temp;
				return temp;
			}
		}
	}
	return 0;
}//带弧优化

int max_flow(int s, int t) {
	int maxflow = 0;
	while (1) {
		find_level(s, t);
		if (level[t] == -1)return maxflow;
		memset(cur, 0, sizeof(cur));
		while (1) {
			int flow = dfs(s, t, INF);
			if (flow == 0)break;
			else maxflow += flow;
		}
	}
}//求最大流

int main() {
	int n, m,s,t;
	while (std::cin >> n >> m>>s>>t) {
		memset(isedge, 0, sizeof(isedge));
		for (int i = 1; i <= n; ++i) {
			G[i].clear();
		}
		for (int i = 1; i <= m; ++i) {
			int x, y, z;
			std::cin >> x >> y >> z;
			add_edge(x, y, z);
		}
		std::cout << max_flow(s, t)<<std::endl;
	}
	return 0;
}