#include<bits/stdc++.h> #include<algorithm> #include<functional> using namespace std; char s[2500]; int main(){ int k; cin>>k; cin>>s; int i=strlen(s); sort(s,s+i,greater<char>()); for(int iu=0;iu<i;++iu){ int n=0; if(s[iu]==s[iu+1]) ++n; if(n==k){ cout<<s[iu]; return 0; } } throw catch; cout<<"No"; return 0; }