Bài 3:
var a,b,c,d:longint;
begin
write('Nhap a,b,c,d: '); readln(a,b,c,d);
if (a>b) and (a>c) and (a>d) then write('So lon nhat la: ',a);
if (b>a) and (b>c) and (b>d) then write('So lon nhat la: ',b);
if (c>b) and (c>a) and (c>d) then write('So lon nhat la: ',c);
if (d>b) and (d>c) and (d>a) then write('So lon nhat la: ',d);
readln;
end.