uses crt;
var a,b,c:real;
D,x1,x2:real;
begin
ClrScr;
repeat
Write('a= ');
Readln(a);
until a<>0;
Write('b=');
Readln(b);
Write('c= ');
Readln(c);
D:=b*b-4*a*c;
if D>0 then
begin
x1:=(-b+sqrt(D))/2*a;
x2:=(-b-sqrt(D))/2*a;
Writeln('x1= ',x1:0:2);
Writeln('x2= ',x2:0:2);
end
else
Writeln('Error!');
Readln;
end.