#include <stdio.h>
long long max[10000],n,k,i=0,j,pozi,m,aux,v[10000];;
int main()
{
    freopen("alibaba.in","r",stdin);
    freopen("alibaba.out","w",stdout);
    scanf("%lld %lld",&n,&k);
    scanf("%lld",&m);
    while(m)   {i++;v[i]=m%10;m/=10;}
    aux=n-k;

    for(j=1;j<=aux;++j)
  {v[pozi]=-1;pozi=0;max[j]=0;
       for(i=1;i<=n;++i)
       if(v[i]!=-1)
	   
	      if(v[i]>max[j])
		{ max[j]=v[i];
		if(i>pozi) pozi=i;
		}
	   
   printf("%lld",max[j]);}
     
     return 0;
     }