ASTRING

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

#define input()                   freopen("C:\\Users\\safayet007\\Desktop\\in.txt", "r", stdin)
#define output()                  freopen("C:\\Users\\safayet007\\Desktop\\out.txt", "w", stdout);
#define FOR(i, a, b)              for(__typeof(b) i = a; i <= b; i++)
#define REP(i, a)                 for(__typeof(a) i = 0; i < a; i++)
#define REPN(i, a)                for(__typeof(a) i = 1; i <= a; i++)
#define ITERATE(it, v)            for(__typeof((v).begin()) it = (v).begin(); it != (v).end(); it++)
#define D(x)                      cout << #x << " = " << (x) << endl
#define all(v)                    (v).begin(), (v).end()
#define SET(a, val)               memset(a, val, sizeof a)
#define pb                        push_back
#define mp                        make_pair
#define endl                      '\n'

typedef long long vlong;
typedef pair <int, int> pii;

struct data {
    char ch; int idx;
};

bool operator < (data x, data y) {
    if(x.ch == y.ch) return x.idx > y.idx;
    else return x.ch < y.ch;
}

int main () {
    //ios_base::sync_with_stdio(false); cin.tie(false);
    int T; scanf("%d", &T);
    while(T --) {
        int k; char str[100005];
        scanf("%s %d", str, &k);
        priority_queue <data> Q;
        int n = strlen(str);
        REP(i, n) {
            data p = {str[i], i};
            Q.push(p);
        }
        int cnt = 0;
        while(not Q.empty()) {
            str[Q.top().idx] = '5'; Q.pop(); cnt ++;
            if(cnt == (n - k)) {
                break;
            }
        }
        REP(i, n) {
            printf(str[i] == '5' ? "" : "%c", str[i]);
        }
        printf("\n");
    }
    return 0;
}