turbo pascal Segitiga

uses wincrt;
var
a,b,c

begin
clrscr;
write('input a =');readln (a);
write('input b =');readln (b);
write('input c =');readln (c);

writeln;
if (a=b) and (b=c) then
write ('segitiga sama sisi')

else if (a=c) then
write ('segitiga siku-siku')

else if (b=c) then
write ('segitiga siku-siku')
else
write ('segitiga sembarang')
readkey;
end.