#include <stdio.h>
#include <stdint.h>
uint16_t binary_to_uint(const char *str)
{
uint16_t val = 0;
for (int i = 0; str[i] != 0; i++)
{
val <<= 1;
if (str[i] == '1')
{
val |= 1;
}
else if (str[i] != '0')
{
return 0xff;
}
// val = (val << 1) | (str[i] - '0');
}
return val;
}
int main() {
char bin[20];
scanf("%s", bin);
printf("%u", binary_to_uint(bin));
return 0;
}