#include <bits/stdc++.h>
using namespace std;
int main(){
	int a,i;
	a=0;
	i=100;
	for(i;i>=0;i-=3) a+=i;
	cout<<a;
	return 0;
	}

/**************************************************************
	Problem: 1053
	User: ljl2
	Language: C++
	Result: Accepted
	Time:4 ms
	Memory:2072 kb
****************************************************************/