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