#include<iostream>

using namespace std;

int main(void)
{       
    int i=100,s=0;
    while(i>=1){
        s+=i;
        i-=3;
        
    }
    cout<<s;
    return 0;
}

/**************************************************************
	Problem: 1053
	User: LYY001
	Language: C++
	Result: Accepted
	Time:3 ms
	Memory:2072 kb
****************************************************************/