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

    }
    long long pow2 = 1;
    for (int i = 0; i < len; i++){
        pow2 *= 2;
    }
    long long singned_value = (long long )
    (unsigned unsigned);
    printf("%lld",signed_value);
    return 0;
}