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  1. #include <bits/stdc++.h>
  2. using namespace std;
  3. using LL = long long;
  4.  
  5. int main() {
  6.  
  7. int n; cin >> n;
  8. vector<int> a(n), b(n);
  9. for (int i = 0; i < n; ++i) {
  10. cin >> a[i] >> b[i];
  11. if ( max(a[i], a[i-1]) > min(b[i], b[i-1])) {
  12. cout << "NO\n";
  13. return 0;
  14. }
  15. }
  16. cout << "YES\n";
  17. }
  18.  
Success #stdin #stdout 0.01s 5320KB
stdin
5
3 6
4 7
2 4
4 5
1 5
stdout
NO