#include <cstdio>
#include <string>

using namespace std;

int main() {
	const string str("atgctgttg");
	const int n = 5; // Assumed positive number smaller than str.size()
	const int n1 = n - 1;

	for (auto i = str.cbegin(); i != str.cend() - n1; ++i) {
		printf("%.*s\n", n, &*i);
	}
}