#include <iostream>
#include <cstring>
#include <algorithm>
using namespace std;
char s[105];
struct point {
int x,y;
}p[105];
bool cmp(point a,point b)
{
if(a.x==b.x) return a.y>b.y;
return a.x>b.x;
}
int main(int argc, char *argv[])
{
int t,i,j,k,a[105],n,m,b;
cin>>t;
while(t--)
{
cin>>s>>k;b=1000;
n=strlen(s);m=n-k;
memset(a,0,sizeof(a));
for(i=0;i<n;i++)
p[i].x=s[i]-'0',p[i].y=n-i;
sort(p,p+n,cmp);
for(i=0;i<m;i++)
for(j=0;j<n;j++)
if(p[j].y>=m-i&&!a[p[j].y]&&b>p[j].y) {b=p[j].y,a[p[j].y]=1,cout<<p[j].x;break;}
cout<<endl;
}
return 0;
}
#include <cstring>
#include <algorithm>
using namespace std;
char s[105];
struct point {
int x,y;
}p[105];
bool cmp(point a,point b)
{
if(a.x==b.x) return a.y>b.y;
return a.x>b.x;
}
int main(int argc, char *argv[])
{
int t,i,j,k,a[105],n,m,b;
cin>>t;
while(t--)
{
cin>>s>>k;b=1000;
n=strlen(s);m=n-k;
memset(a,0,sizeof(a));
for(i=0;i<n;i++)
p[i].x=s[i]-'0',p[i].y=n-i;
sort(p,p+n,cmp);
for(i=0;i<m;i++)
for(j=0;j<n;j++)
if(p[j].y>=m-i&&!a[p[j].y]&&b>p[j].y) {b=p[j].y,a[p[j].y]=1,cout<<p[j].x;break;}
cout<<endl;
}
return 0;
}