#include<stdio.h>
#include<string.h>
int main()
{
    char b[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++ )
        dec =dec*2 +(b[i] -'0');
    }
    
}
if(b[0] =='1')
dec -=(1<< n);
printf("%d",dec);
return 0;
}