$最近颓废了，问题有点多qwq$

$46pts$ $CODE:$

#include<bits/stdc++.h>
#define int long long
#define endl '\n'
using namespace std;
int n,m;
signed main(){
    ios::sync_with_stdio(false);cin.tie(0);cout.tie(0);
    cin>>n>>m;
    map<int,int>k; 
    for(int i=0;i<n;i++){
        int a,b;
        cin>>a>>b;
        k[a]=i+1;
        k[b]=i+1;
    }
    for(int i=0;i<m;i++){
        int x,y;
        cin>>x>>y;
        if(k.count(x)&&k.count(y)&&k[x]==k[y]){
            cout<<k[x]<<endl;
        }else{
            cout<<-1<<endl;
        }
    }
    return 0;
}