Keep Only the Highest Set Bit

#include <stdio.h>
#include <stdint.h>
uint16_t sample;
// Complete the function
uint16_t highest_set_bit(uint16_t reg) {
    // Your logic here
    if(reg==0) return 0;
    else {
        sample=1<<8;
        for(int i=0;i<3;i++)
            if(reg==sample) return sample;
            else if(reg>sample)sample=sample<<(4>>i);
            else if(reg<sample)sample=sample>>(4>>i);
        }
        return sample;
}

int main() {
    uint16_t reg;
    scanf("%hu", &reg);

    uint16_t result = highest_set_bit(reg);
    printf("%hu", result);
    return 0;
}