/*
 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;
}