Extract Even Bits Only from 32-bit Register

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

uint32_t extract_even_bits(uint32_t reg) {
    uint32_t res=1;
    while(reg>0)
    {
        if((reg & 1) == 1 ) res= (res<<1);
        reg=reg>>2;
       // printf("%u\n",reg);

    }
    return res-1;
    
}

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

Solving Approach