Problem p03050 (C++)

Buggy submission (status: Runtime Error):
#include <bits/stdc++.h>
typedef long long ll;
using namespace std;
ll MOD = 1000000007;

#define vec vector<int>
#define vecll vector<ll>
#define vecd vector<double>
#define vecst vector<string>
#define vecb vector<bool>
#define vec2(var, n, m) vector<vector<int>> var(n, vector<int>(m, 0))
#define vecb2(var, n, m) vector<vector<bool>> var(n, vector<bool>(m, false))
#define vecll2(var, n, m) vector<vector<ll>> var(n, vector<ll>(m, 0))

#define rep(i, n) for (ll i = (ll)0; i < (ll)n; i++)
#define REP(i, m, n) for (ll i = (ll)m; i < (ll)n; i++)
#define arr(var, n)                                                            \
  vec var(n);                                                                  \
  rep(i, n) { cin >> var[i]; }
#define arrll(var, n)                                                          \
  vecll var(n);                                                                \
  rep(i, n) { cin >> var[i]; }
#define arrst(var, n)                                                          \
  vecst var(n);                                                                \
  rep(i, n) { cin >> var[i]; }
#define all(var) (var).begin(), (var).end()
#define sortall(var) sort(all(var))
#define uniqueall(v) v.erase(unique(v.begin(), v.end()), v.end());
#define f_sum(var) accumulate(all(var), 0)
#define f_sumll(var) accumulate(all(var), 0LL)
#define chmin(v1, v2) v1 = min(v1, v2)
#define chmax(v1, v2) v1 = max(v1, v2)
#define pb(var) push_back(var)
#define prt(var) cout << (var) << "\n"
#define prtd(n, var) cout << fixed << setprecision(n) << (var) << "\n"
#define prtfill(n, var) cout << setw(n) << setfill('0') << (var);
#define prt2(v1, v2) cout << (v1) << " " << (v2) << "\n"
#define prt3(v1, v2, v3) cout << (v1) << " " << (v2) << " " << (v3) << "\n"
#define prtall(v)                                                              \
  rep(i, v.size()) { cout << v[i] << (i != v.size() - 1 ? " " : "\n"); }
void prtok(bool ok) { prt(ok ? "Yes" : "No"); }
//----------------------------------------------------------------

int main(void) {
  ll n;
  cin >> n;

  ll ans = 0;
  for (ll i = 1; i * i <= n; i++) {
    if (n % i == 0) {
      ll m = n / i - 1;
      if (n / m == n % m)
        ans += m;
    }
  }

  prt(ans);
}


Fixed submission:
#include <bits/stdc++.h>
typedef long long ll;
using namespace std;
ll MOD = 1000000007;

#define vec vector<int>
#define vecll vector<ll>
#define vecd vector<double>
#define vecst vector<string>
#define vecb vector<bool>
#define vec2(var, n, m) vector<vector<int>> var(n, vector<int>(m, 0))
#define vecb2(var, n, m) vector<vector<bool>> var(n, vector<bool>(m, false))
#define vecll2(var, n, m) vector<vector<ll>> var(n, vector<ll>(m, 0))

#define rep(i, n) for (ll i = (ll)0; i < (ll)n; i++)
#define REP(i, m, n) for (ll i = (ll)m; i < (ll)n; i++)
#define arr(var, n)                                                            \
  vec var(n);                                                                  \
  rep(i, n) { cin >> var[i]; }
#define arrll(var, n)                                                          \
  vecll var(n);                                                                \
  rep(i, n) { cin >> var[i]; }
#define arrst(var, n)                                                          \
  vecst var(n);                                                                \
  rep(i, n) { cin >> var[i]; }
#define all(var) (var).begin(), (var).end()
#define sortall(var) sort(all(var))
#define uniqueall(v) v.erase(unique(v.begin(), v.end()), v.end());
#define f_sum(var) accumulate(all(var), 0)
#define f_sumll(var) accumulate(all(var), 0LL)
#define chmin(v1, v2) v1 = min(v1, v2)
#define chmax(v1, v2) v1 = max(v1, v2)
#define pb(var) push_back(var)
#define prt(var) cout << (var) << "\n"
#define prtd(n, var) cout << fixed << setprecision(n) << (var) << "\n"
#define prtfill(n, var) cout << setw(n) << setfill('0') << (var);
#define prt2(v1, v2) cout << (v1) << " " << (v2) << "\n"
#define prt3(v1, v2, v3) cout << (v1) << " " << (v2) << " " << (v3) << "\n"
#define prtall(v)                                                              \
  rep(i, v.size()) { cout << v[i] << (i != v.size() - 1 ? " " : "\n"); }
void prtok(bool ok) { prt(ok ? "Yes" : "No"); }
//----------------------------------------------------------------

int main(void) {
  ll n;
  cin >> n;

  ll ans = 0;
  for (ll i = 1; i * i <= n; i++) {
    if (n % i == 0) {
      ll m = n / i - 1;
      if (m < 1)
        continue;
      if (n / m == n % m)
        ans += m;
    }
  }

  prt(ans);
}