#include<stdio.h>
#include<string.h>
#include<stdin.h>
int main(){
    char binary_str[33];
    if(scanf("%s",binary_str) != 1)return 1;
    int len=strlen(binary_str);
    for(int i = 0;i < len;i++){
        if(binary_str[i] != '0' && binary_str[i] != '1'){
            printf("Invalid Input\n");
            return 0;
        }
    }
    long long result = 0;
    int power = len -1;
    for(int i = 0;i < len; i++){
        result -=(1LL << power);
    }else if(binary_str[i] == '1'){
        result +=(1LL << power);
    }
    power--;
}
printf("%lld\n",result);
return 0;
}