Const
 Max = 10000;
Var
 A: Array [1..Max,0..20] Of Integer;
 Was : Array [1..Max] Of Boolean;
 N,K:Integer;
Procedure DataIn;
 Var
  B,I,J:Integer;
 Begin
{  Assign(InPut,'InPut.txt');
   ReSet(InPut);{}
    FillChar(Was,SizeOf(Was),False);
    ReadLn(N,K);
     For I:=1 To N-1 Do
      Begin
       Read(J,B);
       Inc(A[J,0]);
       A[J,A[J,0]]:=B;
       Inc(A[B,0]);
       A[B,A[B,0]]:=J;
      End;
 End;

Procedure DataOutWin(A:Integer);
  Begin
{  Assign(OutPut,'OutPut.txt');
   ReWrite(OutPut);{}
   Write('First player wins flying to airport ');
   Write(A);
   Halt;
 End;


Procedure DataOutLoose;
 Begin
{  Assign(OutPut,'OutPut.txt');
   ReWrite(OutPut);{}
   WriteLn('First player loses');
   Halt;
 End;

Procedure Work;
Var
 D,I,J,C,C1:Integer;
 List,ExList:Array [1..Max] Of Record
             R:Integer;
             A:Integer;
             End;
 F:Boolean;
 Begin
  C:=1;
  List[1].R:=K;
  Was[K]:=True;
  K:=1;
  D:=0;
  While C<>0 Do
   Begin
    Inc(D);
    C1:=0;
    For I:=1 To C Do
     Begin
      F:=False;
     For J:=1 To A[List[I].R,0] Do
      If Not Was[A[List[I].R,J]] Then
      Begin
       Inc(C1);
       ExList[C1].R:=A[List[I].R,J];
       If D = 1 Then ExList[C1].A:=ExList[C1].R
       Else ExList[C1].A:=List[I].A;
       Was[ExList[C1].R]:=True;
       F:=True;
      End;
      If (Not F) And (K=2) Then DataOutWin(List[i].A);
     End;
     C:=C1;
     List:=ExList;
    K:=3-K;
   End;
 End;

Begin
 DataIn;
  Work;
 DataOutLoose;
End.

"If there are more than one such airports, the program should find
one of them that has the minimal number."

Try this test:
2 1
1 2
1 1

Isn't it supposed to be N-1 lines refering to the conections between
airports?

If so, then the test case you posted is not a valid one.


> Try this test:
> 2 1
> 1 2
> 1 1