uses crt;
var n,d:longint;
{-------------------------------------------------------------}
function soln(x:longint):longint;
var s:string;h,k,m:longint;t:char;
begin
str(x,s);
for h:=1 to length(s)-1 do
for k:=h+1 to length(s) do
if s[h]<s[k] then begin t:=s[h];
s[h]:=s[k];
s[k]:=t;
end;
val(s,m);
soln:=m;
end;
{-------------------------------------------------------------}
function sodx(x:longint):longint;
var h,m:longint;s,s1:string;
begin
s1:='';str(x,s);
for h:=length(s) downto 1 do s1:=s1+s[h];
val(s1,m);
sodx:=m;
end;
{-------------------------------------------------------------}
begin
readln(n);
d:=1;
while n<>6174 do
begin
d:=d+1;
n:=soln(n);
n:=n-sodx(n);
end;
write(d);
readln
end.
