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++ (GCC 9.2.1) (judge verdict: Accepted)

#include <bits/stdc++.h>
#include <ext/pb_ds/assoc_container.hpp>

using namespace __gnu_pbds;
using namespace std;

typedef long long ll;
typedef long double ld;
typedef tree<ll,null_type,less<ll>,rb_tree_tag, tree_order_statistics_node_update> ordered_set;

#define int ll
#define endl "\n"
#define all( x ) x.begin(), x.end()
#define fast ios::sync_with_stdio(0);cin.tie(0);

typedef unsigned long long ull;

const int inf = 1e9 + 5;
const long double PI = 3.141592653589793;

void solve(){
  int x;
  cin >> x;
  cout << (x / 500) * 1000 + ((x % 500) / 5) * 5 << endl;
  return;
}  
signed main(){
  fast;
  int t;
  t = 1;
  //cin>>t;
  while(t--){
    solve();
  }
}