from collections import deque

# tree为邻接表
def search(start, tree):
    n = 100
    visited = [False] * n
    dist = [0] * n
    q = deque()
    q.append(start)
    visited[start] = True
    dist[start] = 0

    while q:
        u = q.popleft()
        for v in tree[u]:
            if not visited[v]:
                visited[v] = True
                dist[v] = dist[u] + 1
                q.append(v)