#include<iostream>
using namespace std;
int main(){
	int i,s;
	i=100;
	s=0;
	while(i>=1){
//		cout<<i<<endl;
		s=s+i;
		
		i=i-3;
	}
		
	cout<<s<<endl;
	
}
/**************************************************************
	Problem: 1053
	User: admin
	Language: C++
	Result: Accepted
	Time:4 ms
	Memory:2072 kb
****************************************************************/