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