#include <bits/stdc++.h>
using namespace std;
int main() {
string s, result;
while(1){
int n;
cin>>n;
cin>>s;
result = "";
if(n == 0) break;
for(int i = 0; i < n; i++){
int flag = 1;
for(int k = i; k < s.length();){
result += s[k];
if(flag == 1){
k += 2*n - 1;
flag = 0;
}
else{
k+= 1;
flag = 1;
}
}
}
cout<< result;
}
return 0;
}
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