N, M, inf = 1010, 20010, float('inf')

h, e, f, ne, idx = [-1] * N, [0] * M, [0] * M, [0] * M, 0

d, pre = [0] * N, [0] * N


def add(a, b, c):
    global idx
    e[idx], f[idx], ne[idx], h[a] = b, c, h[a], idx
    idx += 1


def bfs():
    q = [0] * N
    q[0] = S
    hh, tt = 0, 1

    undo = [True] * N
    undo[S] = False

    d[S] = inf

    while hh < tt:
        u = q[hh]; hh += 1

        i = h[u]
        while i != -1:
            v = e[i]
            if undo[v] and f[i]:
                undo[v] = False
                d[v] = min(d[u], f[i])
                pre[v] = i
                if v == T:
                    return True
                q[tt] = v; tt += 1
            i = ne[i]
    return False


def EK():
    ans = 0
    while bfs():
        ans += d[T]
        i = T
        while i != S:
            f[pre[i]] -= d[T]
            f[pre[i] ^ 1] += d[T]
            i = e[pre[i] ^ 1]
    return ans

n, m, S, T = map(int, input().split())

while m:
    a, b, c = map(int, input().split())
    add(a, b, c); add(b, a, 0)
    m -= 1
print(EK())