#include<stdio.h>
#include<stdlib.h>
#include<string.h>
int main()
{
    char s[33];
    scanf("%s",s);
    for (int i=0;i<strlen(s);i++){
        if (s[i]!='0' && s[i]!='1'
    }
    {
        printf("Invalid Input");
    }
    else
    {
    printf("%d\n",(int)strtol(s,NULL,2));
    }
    return 0;
}