#include<iostream> #include<cstring> #include<cstdio> using namespace std; int main(){ char s[2500]; int k,len,sum = 1,i; cin >> k; cin >> s; len= strlen(s); for(i=0;i<len;i++){ if(sum ==k){ cout << s[i]<< endl; return 0; } if(s[i] == s[i+1]) sum++; else sum = 1; } cout << "No" << endl; return 0; }