#include<bits/stdc++.h>
using namespace std;
int main(){
	int a=100,c=0;
	while(a>=1){
		c=c+a;
		a=a-3;
	}
    cout<<c;
}
/**************************************************************
	Problem: 1053
	User: lvrenxiang
	Language: C++
	Result: Accepted
	Time:4 ms
	Memory:2072 kb
****************************************************************/