Solve in Python:
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-----
1024

-----Sample Output-----
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.
def __starting_point():

    x = int(input())
    
    ans = (x // 500)
    if ans > 0:
        x = x - (500 * ans)
        ans *= 1000
    
    ans += (x // 5) * 5
    print(ans)
__starting_point()