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  1. program flappybird;
  2. Uses Math;
  3. const Maxx =100000;
  4. var N, i : Longint;
  5. A, B : int64;
  6. inizio, fine :int64;
  7. uscita:boolean;
  8. begin
  9. (*assign(input, 'input.txt'); reset(input);
  10.   assign(output, 'output.txt'); rewrite(output);*)
  11. readln(N);
  12. readln(A,B);
  13. inizio:=A; fine:=B; uscita:=true;
  14. for i:=1 to N-1 do
  15. begin
  16. readln(A,B); writeln (A,B);
  17. if ((A>fine) or (B<inizio)) then begin uscita:=false; writeln ('NO'); exit; end;
  18. inizio:=Max (inizio, A);
  19. fine:=Min (fine,B);
  20. end;
  21. if uscita=true then writeln('YES') ;
  22. end.
Success #stdin #stdout 0s 5316KB
stdin
5
3 6
4 7
2 4
4 5
1 5
stdout
47
24
45
15
YES