[Rqnoj-148][NOIP1999]回文数

type
hp=array[0..10000] of longint;
var
n,ans:longint;
a:hp;
function d(c:char):longint;
begin
case c of
'0':d:=0;  '1':d:=1;  '2':d:=2; '3':d:=3;  '4':d:=4;
'5':d:=5;  '6':d:=6;  '7':d:=7; '8':d:=8;  '9':d:=9;
'A':d:=10; 'B':d:=11; 'C':d:=12; 'D':d:=13; 'E':d:=14; 'F':d:=15;
end;
end;
function ok(a:hp):boolean;
var
i,j:longint;
begin
i:=1; j:=a[0]; ok:=true;
while i<j do begin
if a[i]<>a[j] then begin ok:=false; break; end;
inc(i); dec(j);
end;
end;
function fan(a:hp):hp;
var
b:hp;
i:longint;
begin
fillchar(b,sizeof(b),0);
b[0]:=a[0]; for i:=1 to a[0] do b[a[0]-i+1]:=a[i];
fan:=b;
end;
procedure h_jia(a,b:hp;var c:hp);
var
i,len:longint;
begin
if a[0]>b[0] then len:=a[0] else len:=b[0];
fillchar(c,sizeof(c),0);
for i:=1 to len do begin
c[i]:=c[i]+a[i]+b[i];
c[i+1]:=c[i+1]+c[i] div n;
c[i]:=c[i] mod n;
end;
if c[len+1]<>0 then inc(len);
c[0]:=len;
end;
procedure main;
var
s:string;
i:longint;
begin
readln(n); readln(s); fillchar(a,sizeof(a),0);
a[0]:=length(s);
for i:=1 to a[0] do a[a[0]-i+1]:=d(s[i]);
ans:=-1;
for i:=0 to 30 do begin
if ok(a) then begin ans:=i; break end;
h_jia(a,fan(a),a);
end;
if ans=-1 then write('Impossible') else write(ans);
end;
begin
main;
end.