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>

using namespace std;
#define ll long long
#define FOR(i, a, b) for (ll i = (a); i < (b); ++i)
#define REP(i, n) FOR(i, 0, n)
#define PRINT(item) cout << (item) << endl;
#define PRINT_VEC(V)                                                           \
    for (auto v : (V))                                                         \
        cout << v << ' ';
const int MOD = 1000000007;
/* cout << fixed << setprecision(10) << decimal << endl; */

int main() {
    /* code */
    ll X;
    cin >> X;
    ll res = 0;
    while (X >= 0) {
        if (X >= 500) {
            X -= 500;
            res += 1000;
        } else if (X >= 5) {
            X -= 5;
            res += 5;
        } else {
            break;
        }
    }
    cout << res << endl;
    return 0;
}