#include <bits/stdc++.h>

using namespace std;

void FastCode()
{
    std::ios_base::sync_with_stdio(0);
    cin.tie(NULL);
    cout.tie(NULL);
}

void solve(){
    long long n , k;
    cin >> n >> k;
    if(n == 1){
        if(k == 2) cout<<"1\n";
        else cout<<"0\n";
        return;
    }
    int ans = (k-1)/2;
    if(k%2 == 0) ans++;
    cout<<ans<<"\n";
}
int main()
{
    FastCode();
    int t;
    cin >> t;
    while(t--) solve();
    return 0;
}