#include <bits/stdc++.h>
#include <ext/pb_ds/assoc_container.hpp>
#include <ext/pb_ds/tree_policy.hpp>

using namespace std;

using namespace __gnu_pbds;

using ll = long long;
using ull = unsigned long long;
using ld = long double;

template <class __set_element_type>
using gnu_set = tree<__set_element_type, null_type, less<__set_element_type>, rb_tree_tag, tree_order_statistics_node_update>;
template <class __key_type, class __val_type>
using gnu_map = tree<__key_type, __val_type, less<__key_type>, rb_tree_tag, tree_order_statistics_node_update>;

#define ios                  \
    ios::sync_with_stdio(0); \
    cin.tie(0)

const ll oo = 1e18;
const ll MOD = 1e9 + 7;

int t;
ll n, k;

int main()
{
    ios;
    cin >> t;
    while (t--)
    {
        cin >> n >> k;
        ll delim = min(n + 1, k - 1);
        cout << delim / 2 << '\n';
    }
}