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