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)

/* Author : Prasuk Jain */
#include <bits/stdc++.h>
#include <ext/pb_ds/assoc_container.hpp>
using namespace __gnu_pbds;
using namespace std;

#define int              long long int
#define ull              unsigned long long
#define ld               long double
#define fo(i, n)         for(int i=0; i<n; i++)
#define FOR(i, a, b)     for(int i=a; i<b; i++)
#define rfor(i, n)       for(int i=n-1; i>=0; i--)
#define RFOR(i, a, b)    for(int i=b-1; i>=a; i--)
#define tr(it, v)        for(auto it=a.begin(); it!=a.end(); it++)
#define vi               vector<int>
#define pii              pair<int,int>
#define mii              map<int,int>
#define pqb              priority_queue<int>
#define pqs              priority_queue<int,vi,greater<int>>
#define mp               make_pair
#define pb(x)            push_back(x)
#define hcf(x, y)        __gcd(x, y)
#define lcm(x, y)        boost::math::lcm(x,y)
#define setpre(x, y)     fixed << setprecision(y) << x
#define setbits(x)       __builtin_popcountll(x)
#define zerolead(x)      __builtin_clzll(x)
#define zerotrail(x)     __builtin_ctzll(x)
#define all(x)           x.begin(), x.end()
#define sortall(x)       sort(all(x))
#define PI               3.1415926535897932384626
const int mod = 1e9+7;
const int inf = 1e18;
int mpow(int base, int exp);
bool isprime(int num);
void prifact(int num);

//*!*!*!*!*!*!*!*!*!*!*!*!*!*!*!*!*!*!*!*!*!*!*!*!*!*!*!//

void coderprasukj(){ 
    ios_base::sync_with_stdio(false);
    cin.tie(NULL); cout.tie(NULL);
    #ifndef ONLINE_JUDGE
    freopen("input.txt", "r", stdin);
    freopen("output.txt", "w", stdout);
    #endif
}

int32_t main() {
    //coderprasukj();
    int t;
    cin >> t;
    int res=0;
    while(t>=5){
        if(t>=500) {
            t -= 500;
            res += 1000;
        }
        else if(t>5 && t<500){
            t-=5;
            res+=5;
        }
    }
    cout << res << "\n";
    return 0;
}

//*!*!*!*!*!*!*!*!*!*!*!*!*!*!*!*!*!*!*!*!*!*!*!*!*!*!*!//

int mpow(int base, int exp) {
    base %= mod;
    int result = 1;
    while (exp > 0) {
        if (exp & 1) result = ((int)result * base) % mod;
        base = ((int)base * base) % mod;
        exp >>= 1;
    }
  return result;
}

bool isprime(int num) {
    if(num <= 1) return false;
    for(int i=2; i*i <= num; i++)
        if(num%i == 0) return false;
    return true;
}

void prifact(int num){
    for(int i=2; i<=num; i++)
    if(num%i == 0){
        int cnt = 0;
        while(num%i == 0)
        cnt++ , num /= i;
        cout << i << "^" << cnt << " ";
    }
    if(num > 1)
    cout << num << "^" << "1" << " ";
}