Problem p02606 (C++) — buggy submission, verdict: Runtime Error

// #include <tourist>
#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
typedef pair<ll, ll> p;
const ll INF = 1e9;
const ll LINF = ll(1e18);
const ll MOD = 1000000007;
const ll dx[4] = {0, 1, 0, -1}, dy[4] = {-1, 0, 1, 0};
const ll Dx[8] = {0, 1, 1, 1, 0, -1, -1, -1},
         Dy[8] = {-1, -1, 0, 1, 1, 1, 0, -1};
#define yes cout << "Yes" << endl
#define YES cout << "YES" << endl
#define no cout << "No" << endl
#define NO cout << "NO" << endl
#define rep(i, n) for (ll i = 0; i < n; i++)
#define ALL(v) v.begin(), v.end()
#define debug(v)                                                               \\
  cout << #v << ":";                                                           \\
  for (auto x : v) {                                                           \\
    cout << x << ' ';                                                          \\
  }                                                                            \\
  cout << endl;
template <class T> bool chmax(T &a, const T &b) {
  if (a < b) {
    a = b;
    return 1;
  }
  return 0;
}
template <class T> bool chmin(T &a, const T &b) {
  if (b < a) {
    a = b;
    return 1;
  }
  return 0;
}
// cout<<fixed<<setprecision(15);有効数字15桁
//-std=c++14
//-std=gnu++17
ll gcd(ll a, ll b) { return b ? gcd(b, a % b) : a; }
ll lcm(ll a, ll b) { return a / gcd(a, b) * b; }
int main() {
  cin.tie(0);
  ios::sync_with_stdio(false);
  int a, b, c;
  cin >> a >> b >> c;
  int ans = 0;
  for (int i = a; i <= b; i++) {
    if (i % c == 0)
      ans++;
  }
  cout << ans << "\\n";
}


Error: TLE

Fixed submission:

// #include <tourist>
#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
typedef pair<ll, ll> p;
const ll INF = 1e9;
const ll LINF = ll(1e18);
const ll MOD = 1000000007;
const ll dx[4] = {0, 1, 0, -1}, dy[4] = {-1, 0, 1, 0};
const ll Dx[8] = {0, 1, 1, 1, 0, -1, -1, -1},
         Dy[8] = {-1, -1, 0, 1, 1, 1, 0, -1};
#define yes cout << "Yes" << endl
#define YES cout << "YES" << endl
#define no cout << "No" << endl
#define NO cout << "NO" << endl
#define rep(i, n) for (ll i = 0; i < n; i++)
#define ALL(v) v.begin(), v.end()
#define debug(v)                                                               \\
  cout << #v << ":";                                                           \\
  for (auto x : v) {                                                           \\
    cout << x << ' ';                                                          \\
  }                                                                            \\
  cout << endl;
template <class T> bool chmax(T &a, const T &b) {
  if (a < b) {
    a = b;
    return 1;
  }
  return 0;
}
template <class T> bool chmin(T &a, const T &b) {
  if (b < a) {
    a = b;
    return 1;
  }
  return 0;
}
// cout<<fixed<<setprecision(15);有効数字15桁
//-std=c++14
//-std=gnu++17
ll gcd(ll a, ll b) { return b ? gcd(b, a % b) : a; }
ll lcm(ll a, ll b) { return a / gcd(a, b) * b; }
int main() {
  cin.tie(0);
  ios::sync_with_stdio(false);
  int a, b, c;
  int ans = 0;
  for (int i = a; i <= b; i++) {
    if (i % c == 0)
      ans++;
  }
  cout << ans << "\\n";
}