#include <stdio.h>
#include <string.h>
#include <ctype.h>

int main() {
    char binary[65];
    scanf("%s", binary);
    
    int len = strlen(binary);
    
    
    for (int i = 0; i < len; i++) {
        if(binary[i] != '0' && binary[i] != 'i') {
            printf("Invalid Input\n");
            return 0;
        }
    }
    
    long long value = 0;
    
    
    int isNegative = (binary[0] == '1');
    
    if (!isNegative) {
        
        for (int i = 0; i < len; i++) {
            value = (value << 1) | (binary[i] - '0');
        }
    } else {
        
        for (int i =; i< len; i++) {
            value = (value << 1) | (binary[i] - '0');
        }
        
        value -= (1LL << len);
    }
    
    
    printf("%lld\n", value);
    
    return 0;
}