uses crt;
var a, b,c, d, max : integer;
begin
writeln ("so vien loai 1 la",a); readln (a);
writeln ("so vien loai 2 la",b);readln (b);
writeln ("so vien loai 3 la",c); readln (c);
writeln ("so vien loai 4 la",d); readln (d);
max : = 0
if max < a then max : = a;
if max < b then max : = b;
if max < c then max : = c;
if max < d then max : = d;
readln
end.