#include<stdio.h>
#include<string.h>
#include<stdio.h>
int main()
{
    char a[33];
    scanf("%s",a);
    if(strspn(a,"01")!=strlen(a))
    {
        printf("Invalid Input");
        return 0;
    }
    int b=(int)strtol(a,NULL,2);
    if(a[0]=='1')b-=(1<<strlen(a));
    printf("%d",b);
    return 0;
}