#include <stdio.h>
#include <stdint.h>
uint8_t extract_field(uint16_t reg) {
// Your logic here
uint16_t mask = 0x1F0;
uint16_t res = reg & mask;
return res>>4;
return 0;
}
int main() {
uint16_t reg;
scanf("%hx", ®);
printf("%u", extract_field(reg));
return 0;
}