Verified answer

var a,b: integer;

f: text;

begin

assign(f,'input.txt');

reset(f);

read(f,a);

read(f,b);

close(f);

assign(f,'output.txt');

rewrite(f);

if frac(sqrt(a*b))=0 then write(f,trunc(sqrt(a*b)))

else write(f,0);

close(f);

end.