#include <bits/stdc++.h>


using namespace std;

class InParser {
private:
  static const int BUFF_SIZE = 1 << 12;
  FILE *f;
  char buff[BUFF_SIZE];
  int sp = BUFF_SIZE;

  char read_ch() {
    if (sp == BUFF_SIZE) {
      sp = 0;
      fread(buff, 1, BUFF_SIZE, f);
    }
    return buff[sp++];
  }

public:
  InParser() {
    f = stdin;
  }

  InParser& operator >> (int &n) {
    char c;
    while (!isdigit(c = read_ch()) && c != '-');
    int sgn = 1;
    if (c == '-') {
      n = 0;
      sgn = -1;
    } else {
      n = c - '0';
    }
    while (isdigit(c = read_ch())) {
      n = 10 * n + c - '0';
    }
    n *= sgn;
    return *this;
  }

  InParser& operator >> (long long &n) {
    char c;
    n = 0;
    while (!isdigit(c = read_ch()) && c != '-');
    long long sgn = 1;
    if (c == '-') {
      n = 0;
      sgn = -1;
    } else {
      n = c - '0';
    }
    while (isdigit(c = read_ch())) {
      n = 10 * n + c - '0';
    }
    n *= sgn;
    return *this;
  }
};
const int nmax = 1000*1000+5;
int w[nmax],lev[nmax],tt[nmax];
vector<int> v[nmax];
void dfs(int x){
    w[x] = 1;
    for(auto son: v[x])
        if(!w[son]){
           lev[son] = lev[x] + 1;
           tt[son] = x;
           dfs(son);
           w[x] += w[son];
        }
}
int nr1, nr2, nr;
int pathA[nmax], pathB[nmax], path[nmax];
long long sum[nmax];
int lca, n, q;
int a, b, x, y;
void getPath(int A, int B){
    nr1=nr2=nr=0;
    if(lev[A] < lev[B]){
        swap(A,B);
    }
    while(lev[A] > lev[B]){
        pathA[++nr1] = A;
        A=tt[A];
    }
    while(A!=B){
        pathA[++nr1] = A;
        pathB[++nr2] = B;
        A=tt[A];B=tt[B];
    }
    pathA[++nr1] = A;
    for(int i=1;i<=nr1;i++){
        path[i] = pathA[i];
    }
    lca=A;
    nr = nr1+nr2;
    for(int i=1;i<=nr2;i++)
        path[nr1+i] = pathB[nr2-i+1];
}
int getSums(){
    for(int i=1;i<=nr;i++){
        sum[i] = sum[i-1];
        int act = w[path[i]];
        if(i>1&&lev[path[i-1]]>lev[path[i]]){
            act-=w[path[i-1]];
        }
        if(path[i]==lca){
            act+=n-w[path[i]];
        }
        if(i<nr&&lev[path[i+1]]>lev[path[i]]){
            act-=w[path[i+1]];
        }
        sum[i] += act;
    }
}
long long twoPointers(){
    int left=1;
    long long ans=0;
    for(int right=1;right<=nr;right++){
        while(left<right && nr-right+left<right-left){
            left++;
        }
        long long f1=sum[right]-sum[right-1];
        long long f2=sum[left-1];
        ans += 1LL*f1*f2;
    }
    return ans;
}
int main()
{
    //freopen("data.in","r",stdin);
    InParser f;
    f>>n>>q;
    for(int i=1;i<=n-1;i++){
        f>>a>>b;
        v[a].push_back(b);
        v[b].push_back(a);
    }
    dfs(1);
    for(int cnt=1;cnt<=q;cnt++){
        f>>x>>y;
        getPath(x, y);
        getSums();
        cout<<twoPointers()<<'\n';
    }
    return 0;
}