#include <stdio.h>
#include <stdint.h>
uint8_t extract_field(uint16_t reg) {
// Your logic here
uint32_t mask = 0x1F0;
reg = (reg & mask) >> 4;
return reg;
}
int main() {
uint16_t reg;
scanf("%hx", ®);
printf("%u", extract_field(reg));
return 0;
}