#include<bits/stdc++.h>
using namespace std;
int main(){
	int n=100,i=100,a=0;
	while(i>=0){
		a=a+i;
		i=i-3;
	}
	cout<<a;
}
/**************************************************************
	Problem: 1053
	User: linzihang
	Language: C++
	Result: Accepted
	Time:4 ms
	Memory:2072 kb
****************************************************************/