Problem p02724 (C++) — buggy submission, verdict: Runtime Error

#include <bits/stdc++.h>
using namespace std;
#define fast                                                                   \\
  ios_base::sync_with_stdio(false);                                            \\
  cin.tie(NULL)
typedef long long ll;
typedef double dd;
#define pb push_back
#define mp make_pair
#define endl "\\n"
#define M 1000000007
#define pi acos(-1)
/*ll power(ll a,ll b)
{
    ll res = 1;
    while(b > 0)
    {
        if(b & 1)
            res = (res*a)%M;
        a = (a*a)%M;
        b = b >> 1;
    }
    return res;
}*/
/*ll modinv(ll a)
{
   return power(a,M - 2);
}*/
/*vector<ll> primes(ll n)
{
    bool *sieve = new bool[n + 1];
    ll i,j;
    vector<ll> v;
    for(i = 3; i <= n; i+=2)
        sieve[i] = true;
    sieve[2] = true;
    for(i = 3; i*i <= n; i+=2)
    {
        if(sieve[i])
            for(j = i*i; j <= n; j+=i)
                sieve[j] = false;
    }
    if(n >= 2)
    {
        v.pb(2);
        for(i = 3; i <= n; i+=2)
        {
            if(sieve[i])
                v.pb(i);
        }
    }
    return v;
}*/

/*class graph{
public:
    vector<ll> *g;
    ll n;
    graph(ll v)
    {
        n = v + 1;
        g = new vector<ll> [n];
    }
    void addegde(ll f,ll s)
    {
        g[f].pb(s);
        g[s].pb(f);
    }
    void dfs(bool *visited,ll sv)
    {
        visited[sv] = true;
        for(auto x: g[sv])
        {
            if(!visited[x])
            {
                dfs(visited,x);
            }
        }
    }
    void bfs(ll sv){
       queue<ll> q;
       bool visited[n] = {};
       q.push(sv);
       visited[sv] = true;
       while(!q.empty())
       {
           ll node = q.front();
           q.pop();
           for(auto x : g[node])
           {
               if(!visited[x])
               {
                   visited[x] = true;
                   q.push(x);
               }
           }
       }
    }
};*/
int main() {
  fast;
  ll i, j, t;
  cin >> t;
  i = t / 500;
  j = (t - i * 500) / 5;
  cout << (i * 1000 + j * 5) << endl;
  return 0;
}


Error: WA

Fixed submission:

#include <bits/stdc++.h>
using namespace std;
#define fast                                                                   \\
  ios_base::sync_with_stdio(false);                                            \\
  cin.tie(NULL)
typedef long long ll;
typedef double dd;
#define pb push_back
#define mp make_pair
#define endl "\\n"
#define M 1000000007
#define pi acos(-1)
/*ll power(ll a,ll b)
{
    ll res = 1;
    while(b > 0)
    {
        if(b & 1)
            res = (res*a)%M;
        a = (a*a)%M;
        b = b >> 1;
    }
    return res;
}*/
/*ll modinv(ll a)
{
   return power(a,M - 2);
}*/
/*vector<ll> primes(ll n)
{
    bool *sieve = new bool[n + 1];
    ll i,j;
    vector<ll> v;
    for(i = 3; i <= n; i+=2)
        sieve[i] = true;
    sieve[2] = true;
    for(i = 3; i*i <= n; i+=2)
    {
        if(sieve[i])
            for(j = i*i; j <= n; j+=i)
                sieve[j] = false;
    }
    if(n >= 2)
    {
        v.pb(2);
        for(i = 3; i <= n; i+=2)
        {
            if(sieve[i])
                v.pb(i);
        }
    }
    return v;
}*/

/*class graph{
public:
    vector<ll> *g;
    ll n;
    graph(ll v)
    {
        n = v + 1;
        g = new vector<ll> [n];
    }
    void addegde(ll f,ll s)
    {
        g[f].pb(s);
        g[s].pb(f);
    }
    void dfs(bool *visited,ll sv)
    {
        visited[sv] = true;
        for(auto x: g[sv])
        {
            if(!visited[x])
            {
                dfs(visited,x);
            }
        }
    }
    void bfs(ll sv){
       queue<ll> q;
       bool visited[n] = {};
       q.push(sv);
       visited[sv] = true;
       while(!q.empty())
       {
           ll node = q.front();
           q.pop();
           for(auto x : g[node])
           {
               if(!visited[x])
               {
                   visited[x] = true;
                   q.push(x);
               }
           }
       }
    }
};*/
int main() {
  fast;
#ifndef ONLINE_JUDGE
  freopen("input.txt", "r", stdin);
  freopen("output.txt", "w", stdout);
#endif
  ll i, j, t;
  cin >> t;
  i = t / 500;
  j = (t - i * 500) / 5;
  cout << (i * 1000 + j * 5) << endl;
  return 0;
}