#include<stdio.h>
#include<string.h>
int main(){
    char bin[40];
    scanf("%39s",s);
    int n = strlen(s);
    for)(int i=0; i < n; i++){
        if(s[i] != '0'&& s[i] != '1'){
            printf("Invalid Input");
            return 0;
        }
    }
    long long val = 0;
    for (int i =0; i <n; i++){
        val = val * 2 + s[i]-'0');
    }
    if (s[0] == '1'){
        long long base = 1LL << n;
        val = val - base;
    }
    printf("%lld",val);
    return 0;
}