Extract Even Bits Only from 32-bit Register

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

uint32_t extract_even_bits(uint32_t reg) {
    // Your code here
    uint32_t p = 0;
    uint32_t reg_upd = 0;
    while(reg)
    {
        reg_upd = ((reg & 1) << p) | reg_upd;
        reg >>= 2;
        p += 1;
    }

    return reg_upd;
}

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

Solving Approach