#include<stdint.h>
void select ( uint64_t bit, uint64_t * px, uint64_t * py)
{
    uint64_t dummy[4];
    int i;
    for(i=0;i<4; i++)
    {
        if(bit)
        {
            uint64_t tmp = px[i];
            px[i] = py[i];
            py[i] = tmp;
        }
	}
}
int main()
{
    uint64_t a[4];
    uint64_t b[4];
    select(1,a,b);
    select(0,a,b);
    return 0;
}