#include<stdio.h>
#include<string.h>
#include<math.h>
int main()
{
    char binary[33];
    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;
        }
    }
    if(binary[0]=="0"){
        int result =0;
        for(int i=0);i<len; i++){
            result=result*2+(binary[i]-'0');
        }
        printf("%d\n", result);
    }
    else{
        unsigned int result=0;
        for(int i=0;i<len; i++){
            result=result*2+(binary[i]-'0');
        }
        int signedResult=result-(1U<<len);
        printf("%d\n",signedResult);
    }
    res
}