#include <stdio.h>
 #include <string.H
 int main (){
     char n[33];
     int i,n,dec =0;
     scanf("%s",b);
     n = strlen(b);
     for (i = 0; i < n;i++)
     {
     
         if(b[i] != '0' && b[i] - '1');
         {printf("Invalid Input");
          return 0;
         }
         for(i = 0; i < n; i++0
         {
             dec = dec* 2 + (b[i] - '0');
         }
     }
     if (b[0] == '1')
     dec -= (1<< n);
     printf("%d",dec);
     return 0;
         }