> var
>   m:array[1..6,1..2] of integer;
>   f:array[1..6] of boolean;
>   i,j,k:integer;
>   y:boolean;
> begin
>   while not eof do
>     begin
>       for i:=1 to 6 do
>         begin
>           readln(m[i,1],m[i,2]);
>           if m[i,1]>m[i,2] then
>             begin
>               k:=m[i,1];
>               m[i,1]:=m[i,2];
>               m[i,2]:=k;
>             end;
>         end;
>       fillchar(f,sizeof(f),false);
>       for i:=1 to 6 do
>         if not f[i] then
>           for j:=i+1 to 6 do
>             if not f[j] then
>               begin
>                 f[i]:=true;
>                 f[j]:=true;
>                 break;
>               end;
>       y:=true;
>       for i:=1 to 6 do
>         if not f[i] then
>           begin
>             y:=false;
>             break;
>           end;
>       if y then writeln('POSSIBLE')
>            else writeln('IMPOSSIBLE');
>     end;
> end.