#include <stdio.h>
#include<string.h>
int main(){
    char binary[33];
    scanf("%32s",binary);
    int len=strlen(binary);
    for (int i=0;i<len;i++){
        if (binary[i] !='0'&&binary[i] !='1'){
            printf("Invalid Input");
            return 0;
            
        }
    }
    unsigned int value=0;
    for (int i=0;i<len;i++){
        value=(value<<1)|(binary[i]-'0');
        
    }
    if (binary[0]=='1'){
        result=(int)(value-(1U<<len));
    }else{
        result=(int)value;
    }
    printf("%d",result);
    return 0;
}