Problem:
Score : 200 points

Problem Statement

Takahashi loves gold coins. He gains 1000 happiness points for each 500-yen coin he has and gains 5 happiness points for each 5-yen coin he has. (Yen is the currency of Japan.)

Takahashi has X yen. If he exchanges his money so that he will gain the most happiness points, how many happiness points will he earn?

(We assume that there are six kinds of coins available: 500-yen, 100-yen, 50-yen, 10-yen, 5-yen, and 1-yen coins.)

Constraints

0 \leq X \leq 10^9

X is an integer.

Input

Input is given from Standard Input in the following format:

X

Output

Print the maximum number of happiness points that can be earned.

Sample Input 1

1024

Sample Output 1

2020

By exchanging his money so that he gets two 500-yen coins and four 5-yen coins, he gains 2020 happiness points, which is the maximum number of happiness points that can be earned.

Sample Input 2

0

Sample Output 2

0

He is penniless - or yenless.

Sample Input 3

1000000000

Sample Output 3

2000000000

He is a billionaire - in yen.

Solution in C++14 (GCC 5.4.1) (judge verdict: Accepted)

#include <bits/stdc++.h>
#define ll long long
#define IOS ios_base::sync_with_stdio(false);cin.tie(NULL);cout.tie(NULL);
#define deb(x) cout<<#x<<"="<<x<<endl;
#define endl '\n'
#define M 1000000007
#define int long long
#define max_n 1000000

using namespace std;

void solve()
{
	ll x;
	cin>>x;
	ll ans=0;
	ans+=(x/500)*1000;
	x-=(x/500)*500;
	ans+=(x/5)*5;
	x-=(x/5)*5;
	cout<<ans<<endl;
}

int32_t main() 
{
	IOS	
	ll T=1;
	// cin>>T;
	for(ll i=1;i<=T;++i)
	{		
		// cout<<"Case #"<<i<<": ";
    	solve();
	}
	return 0;
}