#include <stdio.h>
#include <string.h>
#include <math.h>
int main()
{
    
    char binary[33];
    scanf("%s", binary);
    int n = strlen(binary);
    for (int i = 0; i < n; i++)
    {
        
        if (binary[i] != '0' && binary[i] != '1')
        {
            printf("Invalid Input");
            return 0;
            }
    
    
long long value = 0;
for (int i = 0; i < n; i++)
{
     value = value*2 + (binary[i] -'0');
}
if(binary[0] == '1')
{
             value -=(1LL << n); 
}
ptintf("%lld\n" , value);
return 0;
}