Extract Even Bits Only from 32-bit Register

#include <stdio.h>
#include <stdint.h>
#define CHECK_BIT(reg, pos) ((reg) & (1 << pos))
#define SET_BIT(reg, pos) ((reg) |= (1 << pos))
uint32_t extract_even_bits(uint32_t reg) {
    // Your code here
    uint32_t ans = 0;
    for (int i = 0; i < 32; i = i + 2){
        if (CHECK_BIT(reg, i)){
            SET_BIT(ans, i / 2);
        }
    }
    return ans;
    
}

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