#include <stdio.h>
#include <srting.h>
#include <math.h>
int main(){
    char bin[33];
    scanf("%s", bin);
    int len = strlen(bin);
    for ( int i = 0; i < len; i++)
    {
        if(bin[i] !='0'&& bin[i] !='1'){
            printf("Ivalid Input\n");
            return 0;
        }
    }
    if (bin[0] == '0'){
        int result = 0;
        for(int i=0;i<len;i++){
            result = result * 2 + (bin[i]-'0');
    }
    printf("%d\n",result);
    }
    else{
        unsigned int result =0;
        for(int i= 0 ;i < len ; i++){
            result = result*2+(bin[i]-'0');
            
        }
        int signedresult = result-(1U << len);
        printf("%d\n",signeresult);
        }
        return 0;
}