## library of LCA by class ## index start from 0 import sys sys.setrecursionlimit(10**5+5) from collections import deque class LCA: def __init__(self,n): self.size = n self.bitlen = n.bit_length() self.ancestor = [[0]*self.size for i in range(self.bitlen)] self.depth = [-1]*self.size self.dis = [-1]*self.size ## using [log_n][n] [n][log_n] ## [log_n][n] is tend to faster than [n][log_n] ## get parent by bfs is probably faster than dfs def make(self,root): self.depth[root] = 0 self.dis[root] = 0 q = deque([root]) while q: now = q.popleft() for nex in e[now]: if self.depth[nex]>= 0: continue self.depth[nex] = self.depth[now]+1 self.dis[nex] = self.dis[now]+1 self.ancestor[0][nex] = now q.append(nex) for i in range(1,self.bitlen): for j in range(self.size): if self.ancestor[i-1][j] > 0: self.ancestor[i][j] = self.ancestor[i-1][self.ancestor[i-1][j]] def lca(self,x,y): dx = self.depth[x] dy = self.depth[y] if dx < dy: x,y = y,x dx,dy = dy,dx dif = dx-dy while dif: s = dif & (-dif) x = self.ancestor[s.bit_length()-1][x] dif -= s while x != y: j = 0 while self.ancestor[j][x] != self.ancestor[j][y]: j += 1 if j == 0: return self.ancestor[0][x] x = self.ancestor[j-1][x] y = self.ancestor[j-1][y] return x def par(self,x,dep): now = x for i in range(self.bitlen)[::-1]: if 1 << i <= dep: now = self.ancestor[i][now] dep -= 1<<i return now n,Q = map(int,input().split()) e = [[] for i in range(n)] for i in range(n-1): a,b= map(int,input().split()) a -= 1 b -= 1 e[a].append(b) e[b].append(a) childs = [0]*n vis = [0]*n q = [0] vis[0] = 1 topo = [] par = [-1]*n while q: now = q.pop() topo.append(now) for nex in e[now]: if vis[nex]: continue par[nex] = now vis[nex] = 1 q.append(nex) for now in topo[::-1]: count = 1 for nex in e[now]: if nex == par[now]: continue count += childs[nex] childs[now] = count lca = LCA(n) lca.make(0) for _ in range(Q): s,t = [int(x)-1 for x in input().split()] if lca.depth[s] < lca.depth[t]: s,t = t,s p = lca.lca(s,t) dis = lca.depth[s]+lca.depth[t] - lca.depth[p]*2 if dis%2: print(0) continue center = lca.par(s,dis//2) if lca.depth[s] == lca.depth[t]: ans = n - childs[lca.par(s,dis//2-1)] - childs[lca.par(t,dis//2-1)] else: ans = childs[center] ans -= childs[lca.par(s,dis//2-1)] print(ans)