#include <bits/stdc++.h>
using namespace std;
int main(void){
    int t;
    cin>>t;
    while(t--){
        long long n,b;
        cin>>n>>b;
        long long mn=0,mx=n-b-1;
        if(mx==-1){
            cout<<n<<endl;
            continue;
        }
        while(mx-mn){
            long long mid=(mx+mn+1)/2;
            if((__int128)(n-b-mid)*((__int128)(mid+1))>=(__int128)(n-mid)*((__int128)(mid))){
                mn=mid;
            }else{
                mx=mid-1;
            }
        }
        cout<<mn+1<<endl;
    }
    return 0;
}