func_code_string: #include <bits/stdc++.h>   using namespace std;   int main() {     long long int MOD = 998244353;     long long int n;     cin >> n;     pair<long long int, long long int> arr[n];     for (long long int i = 0; i < n; ++i) cin >> arr[i].first >> arr[i].second;     long long int fact[n + 1];     fact[0] = 1;     for (long long int i = 1; i <= n; ++i) {       fact[i] = (fact[i - 1] * i + MOD) % MOD;     }     map<long long int, long long int> count1;     map<long long int, long long int> count2;     map<pair<long long int, long long int>, long long int> count3;     for (long long int i = 0; i < n; ++i) {       count1[arr[i].first]++;       count2[arr[i].second]++;       count3[make_pair(arr[i].first, arr[i].second)]++;     }     long long int n1 = 1, n2 = 1, n3 = 1;     map<long long int, long long int>::iterator it;     for (it = count1.begin(); it != count1.end(); ++it) {       n1 = (n1 * (fact[it->second]) + MOD) % MOD;     }     for (it = count2.begin(); it != count2.end(); ++it) {       n2 = (n2 * (fact[it->second]) + MOD) % MOD;     }     map<pair<long long int, long long int>, long long int>::iterator itd;     long long int last2 = -1;     for (itd = count3.begin(); itd != count3.end(); ++itd) {       n3 = (n3 * (fact[itd->second]) + MOD) % MOD;       if (itd->first.second < last2) {         n3 = 0;         break;       }       last2 = itd->first.second;     }     long long int ans = (fact[n] - n1 - n2 + n3 + 2 * MOD) % MOD;     cout << ans;     return 0;   }   