program tim_gia_tri_lon_nhat;

uses crt;

var a, b, c, d: real;

begin

clrscr;

write ('nhap 4 so a, b, c, d: '); readln (a, b, c, d);

if (a>b) and (a>c) and (a>d) then writeln('a la so lon nhat')

else if (b>a) and (b>c) and (b>d) then writeln('b la so lon nhat')

else if (c>a) and (c>b) and (c>d) then writeln('c la so lon nhat')

else if (d>a) and (d>b) and (d>c) then writeln ('d la so lon nhat')

else writeln ('a=b=c=d');

readln

end.