#include <iostream>
using namespace std;
int main() {
int N, sum = 0;
cout << "1 : ";
cin >> N;
if (N < 1) {
cout << "1" << endl;
return 1;
}
for (int i = 1; i <= N; i++) {
sum += i;
}
cout << " 1 " << N << " : " << sum << endl;
return 0;
}
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