#include <stdio.h>
#include <stdint.h>
uint16_t binary_to_uint(const char *str) {
// Your logic here
uint16_t value = 0;
const char * ptr = str;
uint8_t strlen = 0;
while (*ptr++) {
strlen++;
}
for (int i = 0; i < strlen; i++) {
value |= ((str[i]-48) << (strlen-1-i));
}
return value;
}
int main() {
char bin[20];
scanf("%s", bin);
printf("%u", binary_to_uint(bin));
return 0;
}