#include <iostream>
using namespace std;

int main() {
    int sum = 0;
    for (int i = 100; i >= 1; i -= 3) {
        sum += i;
    }
    cout << sum << endl;
    return 0;
}
/**************************************************************
	Problem: 1053
	User: fuyijun
	Language: C++
	Result: Accepted
	Time:4 ms
	Memory:2072 kb
****************************************************************/