> #include <stdio.h>
> #define outerror() {printf("such number is impossible!\n");break;}
> void main()
> {
>  char str[1000];
>  int x,max=0;
>  char* ch;
>  while(scanf("%s",str)==1)
>  {
>   ch=str; 
>   max=0;x=0;
>   while(*ch)
>   {
>    if(str[0]=='0')outerror();
>    if((*ch>='0')&&(*ch<='9'))x=*ch-'0';
>      else if((*ch>='A')&&(*ch<='Z'))x=*ch-'A'+10;
>        else x=*ch-'a'+36;
>    if(x>max)max=x;
>    ch++;
>   }
>   if(max!=0)printf("%d\n",max+1);
>  }
> }