Problem p02829 (C++)

Buggy submission (status: Runtime Error):
/*

साहिल पे पहुंचने से इनकार किसे है लेकिन,
तूफ़ानो से लड़ने का मज़ा ही कुछ और है,
कहते है, कि किस्मत खुदा लिखता है लेकिन,
उसे मिटा के खुद गढ़ने का मजा ही कुछ और है।

*/

#include <bits/stdc++.h>
// #include <ext/pb_ds/assoc_container.hpp>
// #include <ext/pb_ds/tree_policy.hpp>
// using namespace __gnu_pbds;
using namespace std;

#define int long long int
#define ull unsigned int
#define ld long double
#define pb push_back
#define ff first
#define ss second
#define S(arr) sort(arr.begin(), arr.end());
#define RS(arr) sort(arr.rbegin(), arr.rend());
#define R(arr) reverse(arr.begin(), arr.end());
#define si set<int>
#define vi vector<int>
#define vvi vector<vector<int>>
#define vs vector<string>
#define pii pair<int, int>
#define vpi vector<pii>
#define vpp vector<pair<int, pii>>
#define mii map<int, int>
#define mci map<char, int>
#define mpi map<pii, int>
#define spi set<pii>
#define speed                                                                  \
  ios_base::sync_with_stdio(0);                                                \
  cin.tie(0);                                                                  \
  cout.tie(0);
#define endl "\n"
#define all(p) p.begin(), p.end()
#define T                                                                      \
  int tcf;                                                                     \
  cin >> tcf;                                                                  \
  while (tcf--)
#define que_max(t) priority_queue<t>
#define que_min(t) priority_queue<t, vector<t>, greater<t>>
#define debuga(a, l, r)                                                        \
  for (auto x : a)                                                             \
    cout << x << " ";                                                          \
  cout << endl;
#define debug1(x) cout << #x " = " << x << endl;
#define debug2(x, y) cout << #x " = " << x << " " << #y " = " << y << endl;
#define debug3(x, y, z)                                                        \
  cout << #x " = " << x << " " << #y " = " << y << " " << #z " = " << z << endl;
#define debug4(x, y, z, w)                                                     \
  cout << #x " = " << x << " " << #y " = " << y << " " << #z " = " << z << " " \
       << #w " = " << w << endl;
#define debug5(x, y, z, w, v)                                                  \
  cout << #x " = " << x << " " << #y " = " << y << " " << #z " = " << z << " " \
       << #w " = " << w << " " << #v " = " << v << endl;
#define debug6(x, y, z, w, v, a) debug3(a, y, x) debug3(w, v, a)
#define p2d(v)                                                                 \
  for (auto a : v) {                                                           \
    for (auto b : a)                                                           \
      cout << b << " ";                                                        \
    cout << endl;                                                              \
  }
#define p1d(v)                                                                 \
  for (auto a : v)                                                             \
    cout << a << " ";                                                          \
  cout << endl;
#define ppi(v)                                                                 \
  for (auto a : v)                                                             \
    cout << a.ff << " " << a.ss << endl;

void read(int n = 10) {
  ios_base::sync_with_stdio(0);
  cin.tie(0);
  cout.tie(0);
  cout << setprecision(n) << fixed;
#ifndef ONLINE_JUDGE
  freopen("input.txt", "r", stdin);
  freopen("output.txt", "w", stdout);
#endif
}

int M = 1e9 + 7;
int M1 = 998244353;
#define qqq 4000005

int32_t main() {
  read();
  int a, b;
  cin >> a >> b;
  cout << 6 - a - b;
}

Fixed submission:
/*

साहिल पे पहुंचने से इनकार किसे है लेकिन,
तूफ़ानो से लड़ने का मज़ा ही कुछ और है,
कहते है, कि किस्मत खुदा लिखता है लेकिन,
उसे मिटा के खुद गढ़ने का मजा ही कुछ और है।

*/

#include <bits/stdc++.h>
// #include <ext/pb_ds/assoc_container.hpp>
// #include <ext/pb_ds/tree_policy.hpp>
// using namespace __gnu_pbds;
using namespace std;

#define int long long int
#define ull unsigned int
#define ld long double
#define pb push_back
#define ff first
#define ss second
#define S(arr) sort(arr.begin(), arr.end());
#define RS(arr) sort(arr.rbegin(), arr.rend());
#define R(arr) reverse(arr.begin(), arr.end());
#define si set<int>
#define vi vector<int>
#define vvi vector<vector<int>>
#define vs vector<string>
#define pii pair<int, int>
#define vpi vector<pii>
#define vpp vector<pair<int, pii>>
#define mii map<int, int>
#define mci map<char, int>
#define mpi map<pii, int>
#define spi set<pii>
#define speed                                                                  \
  ios_base::sync_with_stdio(0);                                                \
  cin.tie(0);                                                                  \
  cout.tie(0);
#define endl "\n"
#define all(p) p.begin(), p.end()
#define T                                                                      \
  int tcf;                                                                     \
  cin >> tcf;                                                                  \
  while (tcf--)
#define que_max(t) priority_queue<t>
#define que_min(t) priority_queue<t, vector<t>, greater<t>>
#define debuga(a, l, r)                                                        \
  for (auto x : a)                                                             \
    cout << x << " ";                                                          \
  cout << endl;
#define debug1(x) cout << #x " = " << x << endl;
#define debug2(x, y) cout << #x " = " << x << " " << #y " = " << y << endl;
#define debug3(x, y, z)                                                        \
  cout << #x " = " << x << " " << #y " = " << y << " " << #z " = " << z << endl;
#define debug4(x, y, z, w)                                                     \
  cout << #x " = " << x << " " << #y " = " << y << " " << #z " = " << z << " " \
       << #w " = " << w << endl;
#define debug5(x, y, z, w, v)                                                  \
  cout << #x " = " << x << " " << #y " = " << y << " " << #z " = " << z << " " \
       << #w " = " << w << " " << #v " = " << v << endl;
#define debug6(x, y, z, w, v, a) debug3(a, y, x) debug3(w, v, a)
#define p2d(v)                                                                 \
  for (auto a : v) {                                                           \
    for (auto b : a)                                                           \
      cout << b << " ";                                                        \
    cout << endl;                                                              \
  }
#define p1d(v)                                                                 \
  for (auto a : v)                                                             \
    cout << a << " ";                                                          \
  cout << endl;
#define ppi(v)                                                                 \
  for (auto a : v)                                                             \
    cout << a.ff << " " << a.ss << endl;

void read(int n = 10) {
  ios_base::sync_with_stdio(0);
  cin.tie(0);
  cout.tie(0);
  cout << setprecision(n) << fixed;
#ifndef ONLINE_JUDGE
  freopen("input.txt", "r", stdin);
  freopen("output.txt", "w", stdout);
#endif
}

int M = 1e9 + 7;
int M1 = 998244353;
#define qqq 4000005

int32_t main() {
  // read();
  ios_base::sync_with_stdio(0);
  cin.tie(0);
  cout.tie(0);

  int a, b;
  cin >> a >> b;
  cout << 6 - a - b;
}