Program TreeAnalize;
Uses CRT;
Const MaxSize = 20;
Var a: Array[1..MaxSize, 1..MaxSize] of Byte;
     i,j: Byte;
     n: Byte;

Procedure WriteMatrix;
Begin
Write('How many vertex?: '); Readln(n);
Writeln('e.g. "[1 -> 3]: 1" if ver.3 & ver.1 - linked');
Writeln('e.g. "[2 -> 5]: 0" if ver.2 & ver.5 - no linked');
Writeln;
For i := 1 to n-1 do
     Begin
     For j := i + 1 to n do
         Begin
         Write('[',i,' -> ',j,']: ');
         Readln(a[i,j]);
         a[j,i] := a[i,j];
         End;
     End;
End;

Procedure PrintMatrix;
Begin
Writeln;
For i := 1 to n do
     Begin
     For j := 1 to n do
         Write(a[i,j]:4);
     Writeln;
     End;
End;

Function AnalizeMatrix: Boolean;
Var col: boolean;
     k: Byte;
     result: Boolean;
Begin
result := True;
For i := 2 to n do
     Begin
     Col := false;
     For j := 1 to i do
         Begin
         if (a[i,j] = 1) then
            Begin
            if (Col = false) then Col := True
                             else Begin
                    result := false;
                    Write('Loop in: ',j,' -> ', i);
                    For k := j-1 downto 1 do
                    if (a[i,k] = 1) then
                    Begin
                    Writeln(' -> ',k);
                    Break
                    End;
                    End;
            End;
         End;
     End;
AnalizeMatrix := result;
End;

Begin
ClrScr;
WriteMatrix;
PrintMatrix;
ReadKey;
if (AnalizeMatrix) then Writeln('Clear!!!')
                    else Writeln('Loop found!');
ReadKey;
End.