/*
uva - 10093
written by shaheen
*/
#include<iostream>
#include<cstring>
#include<cstdio>
#include<cctype>
using
namespace
std
;
int
main
(
)
{
string s
;
while
(
cin
>>
s
)
{
int
base
=
2
,n,sum
=
0
;
int
len
=
s.
length
(
)
;
for
(
int
i
=
0
;
i
<
len
;
i
++
)
{
n
=
0
;
if
(
isdigit
(
s
[
i
]
)
)
{
n
=
s
[
i
]
-
48
;
sum
+
=
n
;
if
(
n
+
1
>
base
)
base
=
n
+
1
;
}
else
if
(
isupper
(
s
[
i
]
)
)
{
n
=
s
[
i
]
-
'A'
+
10
;
sum
+
=
n
;
if
(
n
+
1
>
base
)
base
=
n
+
1
;
}
else
if
(
islower
(
s
[
i
]
)
)
{
n
=
s
[
i
]
-
'a'
+
36
;
sum
+
=
n
;
if
(
n
+
1
>
base
)
base
=
n
+
1
;
}
}
bool
flag
;
for
(
int
j
=
base
;
n
<=
62
;
j
++
)
if
(
sum
%
(
j
-
1
)
==
0
)
{
printf
(
"%d
\n
"
,j
)
;
flag
=
true
;
break
;
}
if
(
!
flag
)
printf
(
"such number is impossible!
\n
"
)
;
s.
clear
(
)
;
}
return
0
;
}