#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 lonh=g value =0;
for(int i = 0; i < n; i++)
{
    value = value*2 + (binary[i] - '0');
}
if(binary[0] == '1')
{
    value -=(1LL << n);
}
printf("%lld\n",value)'
return 0;
}