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