#include<stdio.h>
#include<string.h>
#include<stdlib.h>
int main() {
    char binary_string[33];
    scanf("%s", binary_string);
    
    int len = strlen(binary_string);
    if (len > 32) {
        printf("Invalid Input\n");
        return 0;
    }
    for (int i = 0; i < len; i++) {
        if (binary_string[i] != '0' && binary_string[i] != '1') {
            printf("Invaid Input\n");
            return 0;
        }
    }
    long long decimal_value = 0;
    int sign = 1;
    
    if (binary_string[0] == '1') {
        sign = -1;
    }
    for (int i = len - 1;i >= 0; i--){
        if (binary_string[i] == '1'){
            decimal_value += pow(2, (len - 1) - i)
        }
    }
    if (sign == -1){
        decimal_value -= pow(2, len);
    }
    printf("%11d\n", decimal_value);
    return 0;
}