#include<bits/stdc++.h>
using namespace std;
int main()
{int i=100,sum=0;
 while(i>=1){
   sum+=i;
    i-=3;
 }   
 cout<<sum<<endl;
  	return 0;
}

/**************************************************************
	Problem: 1053
	User: czr
	Language: C++
	Result: Accepted
	Time:11 ms
	Memory:2072 kb
****************************************************************/