Begin
var a, b, c: single;
readln(a, b, c);
writeln(max(a, max(b, c)) - min(a, min(b, c)));
end.
Позязя, расширеннее...
begin
var a, b, c, d, e: single;
readln(a, b, c);
if (a < b) then
d := a
else
d := b;
if (c < d) then
d := c;
if (a > b) then
e := a
else
e := b;
if (c > e) then
e := c;
writeln(e - d);
end.