#include<bits/stdc++.h>
using namespace std;
int main()
{
    int n,i;
    string s,s1,res;
    getline(cin,s);
    cin>>n;
    for(i=0;i<s.size();i++)
    if(s[i]>='0'&&s[i]<='9') s1+=s[i];
    stack<char> s2;
    for(i=0;i<s1.size();i++)
    {
        while(!s2.empty()&&s2.top()<s[i]&&(s2.size()-1+s1.size()-i)>=n) s2.pop();
        if(s2.size()<n) s2.push(s1[i]);
    }
    while(!s2.empty())
    {
        res=s2.top()+res;
        s2.pop();
    }
    cout<<res;
}
 

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2