#include<stdio.h>
#include<string.h>
int main()
{
    char bin[40];
    scanf("%s",bin);
    
    int len = strlen(bin);
    int i;
    for (i=0;i<len;i++)
    {
        if(bin[i]!= '0'&& bin[i]!= '1')
        {
        printf("Invalid Input");
        return 0;
    }
    
}

  if(bin[0]=='0'){
      int value = 0;
      for(int i = 0;i< len; i++)
  {
      value = value * 2 + (bin[i] - '0');
  }
      printf("%d",value);
      return 0;
  }
  
  
  
  int i;
  char inv[40];
  for(i = 0; i<len;i++) {
      inv[i] = (bin[i] == '0')? '1':'0';
  }
  
  
  int carry = 1
  for ( i = len - 1;i>=0;i--);{
  int bit = inv[i] - '0';
  int sum = bit + carry;
  inv[i] = (sum % 2) + '0';
  carry = sum / 2;
  
  }
  
  int value = 0;
  for ( i = 0; i < len;i++){
      value = value * 2 + (inv[i] - '0');
      }
  printf("%d", -value);
  return 0;
  }