#include<stdio.h>
#include<string.h>
int main()
{
    char binary[33];
    scanf("%s",binary);
    int n = strlen(binary);
    for(int i = 0; i<n; i++)
    {
        if ( binary[i]! ='0' && binary[i]!='1')
        {
            printf("invalid input");
            return 0;
        }
    } 
    int result=0;
    if (binary[0]=='1')
    {
        for (int i=0; : i<n; i++){
            result =(result<<1) | (binary[i]-'0');
     }
     result= result -(1 << n);
    }else{
        for (int i= 0 ;i< n ; i++){
            result = (result<<1)| (binary[i] -'0');
        }
    }
    printf("%d",result);
    return 0;
}