22. Extract Even Bits Only from 32-bit Register

#include <stdio.h>
#include <stdint.h>

uint32_t extract_even_bits(uint32_t reg) {
     uint32_t result = 0, mask = 1, pos = 0;
    while (mask) {
        if (reg & mask)
            result |= (1 << pos++);
        else
            pos++;
        mask <<= 2;  
    }
    return result;
}

int main() {
    uint32_t reg;
    scanf("%u", &reg);
    printf("%u", extract_even_bits(reg));
    return 0;
}