def DFS(node, finish, parent=-2):
    global edges, mark
    if mark[node] != -1:
        return False
    mark[node] = parent
    if (node == finish):
        return True
    for child in range(len(edges[node])):
        if (edges[node][child]):
            if DFS(child, finish, parent=node):
                return True
    return False

n = int(input())
m = int(input())
edges = [0]*n
for i in range(n):
    edges[i] = [0] * n
for i in range(m):
    a, b = map(int, input().split())
    edges[a][b] += 1
mark = [-1] * n
start, finish = map(int, input().split())
DFS(start, finish)
print(mark)