#include <bits/stdc++.h>
using namespace std;

int main(){
    ios_base::sync_with_stdio(false);
    cin.tie(nullptr);
    
    int T; cin >> T;
    while(T--){
        long long X,Y; cin >> X >> Y;
        X -= Y;
        long long low = 0,high = X+1;
        while(high-low > 1){
            long long mid = (high+low)/2;
            __int128_t a = X-mid+1,b = Y;
            if(a >= b*(mid-1)) low = mid;
            else high = mid;
        }
        cout << low << "\n";
    }
}