#include<stdio.h>
#include<string.h>
#include<ctype.h>
#include<math.h>
int main()
{
    char binary[33];
    scanf("%s",binary);
    int len = strlen(binary);
    for(int i=0;i < len;i++);
    {
        if(binary[i] != '0' && binary[i] != '1')
        {
            printf("Invalid Input");
            return 0;
        }
    }
    int result =0;
    if(binary[0] == '0')
    {
        for(int i=0;i<len;i++)
        {
            result = result*2 + (binary[i] - '0');
        }
    }
    else
    {
        unsigned int value = 0;
        for(int i=0;i < len;i++)
        {
            value = value*2 + (binary[i] - '0');
        }
        result = (int)(value - ( 1U << len));
    }
    printf("%d",result);
    return 0;
}