uses crt;
var scs,i:byte;
mul,n:longword;
function check(n:longint):boolean;
begin
check:=true;
while n > 9 do
begin
if n mod 10 <> 0 then
check:=false;
inc(scs);
n:=n div 10;
end;
inc(scs);
end;
begin
clrscr;
readln(n);
if n = 0 then write(0) else
if n < 10 then write(10-n) else
if check(n) = true then write(0) else
begin
mul:=1;
for i:=1 to scs-1 do
mul:=mul*10;
if n div mul = 9 then write(mul*10-n) else
write((n div mul + 1)*mul - n);
end;
readln;
end.