Extract the Nibble from an 8-bit Register

Code

#include <stdio.h>

unsigned char extractNibble(unsigned char reg, int pos) {
    // Write your code here
    if (reg < 0 || (pos != 0 && pos !=1)){
        return -1;
    } 
    unsigned int  Res;
    if (pos == 0){
        Res = reg & 0x0F;
    }
    if (pos == 1){
    Res = (reg >> 4) & 0x0F;
    }

    return Res;
}

int main() {
    unsigned char reg;
    int pos;
    scanf("%hhu %d", &reg, &pos);
    printf("%d", extractNibble(reg, pos));
    return 0;
}

Solving Approach