#include<bits/stdc++.h>
using namespace std;
int main(){
int n=100,m=0;
while (n>0){
m=m+n;
n=n-3;
}cout<<m;
}
/**************************************************************
	Problem: 1053
	User: sucongyi
	Language: C++
	Result: Accepted
	Time:10 ms
	Memory:2072 kb
****************************************************************/