#include<iostream> 

using namespace std;

int main()
{
	
	int sum=0;
	int i=100;
	
	while(i>=1){
		
		sum+=i;
		i-=3;
	}
	
	cout<<sum<<endl;
	return 0;
}
/**************************************************************
	Problem: 1053
	User: 231308061
	Language: C++
	Result: Accepted
	Time:5 ms
	Memory:2072 kb
****************************************************************/