#include <iostream>
#include <cstring>
#include <algorithm>
using namespace std;
const int N = 10010, M = 200010, INF = 0x3f3f3f3f;
int n, m, S, T, h[N], e[M], ne[M], idx, f[M], d[N], cur[N], q[N];
void add(int a, int b, int c)
{
e[idx] = b, ne[idx] = h[a], f[idx] = c, h[a] = idx ++;
e[idx] = a, ne[idx] = h[b], f[idx] = 0, h[b] = idx ++;
}
//宽搜1、有没有增广路; 2、建立分层图
bool bfs()
{
int hh = 0, tt = 0;
memset(d, -1, sizeof d);
q[0] = S, d[S] = 0, cur[S] = h[S];
while(hh <= tt)
{
int t = q[hh ++];
for(int i = h[t]; ~i; i = ne[i])
{
int ver = e[i];
if(d[ver] == -1 && f[i])
{
d[ver] = d[t] + 1;
cur[ver] = h[ver];
if(ver == T) return true;
q[ ++ tt] = ver;
}
}
}
return false;
}
int find(int u, int limit)
{
if(u == T) return limit;
int flow = 0;
for(int i = cur[u]; ~i && flow < limit; i = ne[i])
{
cur[u] = i;
int ver = e[i];
if(d[ver] == d[u] + 1 && f[i])
{
int t = find(ver, min(f[i], limit - flow));
if(!t) d[ver] = -1;
f[i] -= t, f[i ^ 1] += t, flow += t;
}
}
return flow;
}
int dinic()
{
int r = 0, flow;
while(bfs()) while(flow = find(S, INF)) r += flow;
return r;
}
int main()
{
cin >> n >> m >> S >> T;
memset(h, -1, sizeof h);
while(m --)
{
int a, b, c;
cin >> a >> b >> c;
add(a, b, c);
}
cout << dinic() << endl;
}