class UnionFind: def __init__(self, n): self.parent = [-1] * n self.rank = [1] * n self.count = [1] * n def get_root(self, i): while self.parent[i] != -1: i = self.parent[i] return i def is_same_tree(self, i, j): return self.get_root(i) == self.get_root(j) def merge(self, i, j): i = self.get_root(i) j = self.get_root(j) if i == j: return if self.rank[i] > self.rank[j]: self.parent[j] = i self.rank[i] = max(self.rank[i], self.rank[j] + 1) self.count[i] += self.count[j] else: self.parent[i] = j self.rank[j] = max(self.rank[j], self.rank[i] + 1) self.count[j] += self.count[i] n, m, s, t = map(int, input().split()) assert 2<=n<=10**5 and 1<=m<=10**5, 1<=s<=n and 1<=t<=n assert s != t s -= 1 t -= 1 p = [int(i) for i in input().split()] assert 1<=min(p) <= 10**9 and 1<=max(p) <= 10**9 pd = {} for ind, i in enumerate(p): if i not in pd: pd[i] = [] pd[i].append(ind) ss = set() e = [[] for _ in range(n)] for _ in range(m): a, b = [int(i) - 1 for i in input().split()] assert a