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