#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] !='1')
        {
            printf("Invalid Input");
            return 0;
        }
    }
    if (binary[0]=='0')
    {
        int decimal = 0;
        for (int i = 0; i <len; i++)
        {
            if(binary[i] == '1')
            {
                decimal +=pow(2, len - i -1);
            }
        
        }
        printf("%d", decimal);
    }
    else
    {
        int decimal = 0;
        for (int i =0;i<len;i++)
        {
            if (binary[i] == '1')
            {
    }       
    return 0;
}