#include <bits/stdc++.h>

using namespace std;

const int maxN = 1e5 + ;

map<int, int> cnt, Max, t;

int pre[maxN];

int n, m;

int judge(){

    int sum = , k = , ans = -;

    for(auto it = Max.rbegin(); it != Max.rend(); it++){

        int a = it -> first, b = it -> second; //a是次数， b是该次数下最大的数

        k += t[a];//k是当前有多少种数

        sum += a * t[a]; //只考虑自己和次数比自己大的数的总数

        int minDel = sum - (a-) * k - ;  //要减去的数

        if(minDel <= m){//只要该数小于等于m即可， 剩下的m - minDel随便减

            ans = max(ans, b);

        }

    }

    return ans;

}

int main() {

    int T;

    scanf("%d", &T);

    while(T--) {

        cnt.clear();

        Max.clear();

        t.clear();

        scanf("%d %d", &n, &m);

        for(int i = ; i < n; i++) {

            int num;

            scanf("%d", &num);

            cnt[num]++;

        }

        for(auto it : cnt){

            int a = it.first, b = it.second;

            Max[b] = max(Max[b], a);

            t[b]++;

        }

        printf("%d\n", judge());

    }

}