// editor2
#include<stdio.h>
#include<string.h>
#include<ctype.h>
int main()
{
    char binary[33];
    int length, i;
    int isValid=1;
    scanf("%s",binary);
    length=strlen(binary);
    for (i=0;i<length;++i)
    {
        if (binary[i]!='0'&&binary[i]!='1')
        {
            isValid=0;
            break;
        }
    }
    if(!isValid||length>32)
    {
        printf("Invalid Input\n");
        return 0;
    }
    int value=0;
    if (binary[0]=='1')
    {
        value+=(1<<(length-i-1));
    }
    if(binary[0]=='0')
{
    value=0;
    for(i=0;i<length;i++)
    if(binary[i]=='1')
    {
        value+=(1<<(length-i-1));
    }
printf("%d\n",value);
return 0;
}