#include <iostream>
using namespace std;
int main()
{
	int c=0;
	for(int i=100;i>=0;i=i-3){
		c=c+i;
	}
	cout<<c;
	return 0;
}
/**************************************************************
	Problem: 1053
	User: xuanhua
	Language: C++
	Result: Accepted
	Time:4 ms
	Memory:2072 kb
****************************************************************/