tecnomate.cpp

#include <iostream>
#include <string>
#include <algorithm>
#include <iterator>
#include <vector>

using namespace std;

int main(){
	
	int n, cnt = 0, i;
	string s, answer, aux;
	vector<char> vec;

	cin >> n >> s;
	
	for (i = 0; i < s.size() / n ; i++){
			if(i % 2 == 0) answer[cnt] = s[i*n];
			else{
				aux = s.substr(i*n, i*n + n - 1);
				reverse(aux.begin() , aux.end());
				answer[cnt] = aux[i*n];
			}
			cnt++;
	}
	
	cout << answer;

	return 0;
}