import sys
input = sys.stdin.readline

N,M,S,T=list(map(int,input().split()))

from scipy.sparse import csr_matrix
from scipy.sparse.csgraph import maximum_flow

src=[]
dst=[]
cap=[]

for i in range(M):
    u,v,c=list(map(int,input().split()))
    u-=1
    v-=1
    src.append(u)
    dst.append(v)
    cap.append(c)
    
graph = csr_matrix((cap, (src, dst)), shape=(N, N), dtype=int)
res = maximum_flow(graph, S-1, T-1)

print(res.flow_value)