#include <bits/stdc++.h>
using i64 = long long;

void solve() {
    i64 n, k;
    std::cin >> n >> k;
    std::vector<i64> v(n + 1);
    for(int i = 1; i <= n; ++i) {
        std::cin >> v[i];
        v[i] = v[i] - i + n;
        //std::cout << v[i] << " \n"[i == n];
    }
    std::multiset<i64> st1, st2;
    i64 sum1 = 0, sum2 = 0;
    auto balance = [&](int k) ->void {
        while(st1.size() > k) {
            i64 val = *st1.rbegin();
            sum1 -= val, sum2 += val;
            st1.extract(val);
            st2.insert(val);
        }
        while(st1.size() < k && st2.size()) {
            i64 val = *st2.begin();
            sum1 += val, sum2 -= val;
            st1.insert(val);
            st2.extract(val);
        }
        while(st1.size() == k && st2.size() >= 1) {
            i64 val1 = *st1.rbegin(), val2 = *st2.begin();
            if(val1 > val2) {
                st1.extract(val1);
                st2.extract(val2);
                st1.insert(val2);
                st2.insert(val1);
                sum1 = sum1 - val1 + val2;
                sum2 = sum2 - val2 + val1;
            } else {
                break;
            }
        }
    };
    auto insert = [&](i64 val) ->void {
        st1.insert(val);
        sum1 += val;
    };
    auto erase = [&](i64 val) ->void {
        if(st1.find(val) != st1.end()) {
            st1.extract(val);
            sum1 -= val;
        } else {
            st2.extract(val);
            sum2 -= val;
        }
    };

    int ans = 1;
    for(int i = 1, j = 1; j <= n; ++j)  {
        insert(v[j]);
        while(true) {
            int len = (j - i + 1);
            balance((len + 1) / 2);
            i64 target = *st1.rbegin();
            i64 x = st1.size(), y = st2.size();
            i64 res = 1LL * target * x - sum1 + sum2 - 1LL * target * y; 
            if(res > k) {
                erase(v[i]);
                ++i;
            } else {
                ans = std::max(ans, j - i + 1);
                //std::cout << i << ' ' << j << ' ' << target << ' ' << res << '\n';
                break;
            }

        }
    }
    std::cout << ans << '\n';
}


int main() {
    std::ios::sync_with_stdio(false);
    std::cin.tie(nullptr);
    int T = 1;
    std::cin >> T;
    while(T--) {
        solve();
    }
}