#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 << 1) || (binary[i] - '0');
}
if(binary[0] == '1')
{
    value -=(1LL << n);
}
printf("%lld\n", value);
return 0;
}