极致的输出

#include <cstdio>

int main() {
register int n;
scanf("%d", &n);
const unsigned char flag = (n%30) | ((n%50)<<1) | ((n%7==0)<<2);
switch (flag) {
case 7: printf("3 5 7\n"); break;
case 3: printf("3 5\n"); break;
case 5: printf("3 7\n"); break;
case 6: printf("5 7\n"); break;
case 1: printf("3\n"); break;
case 2: printf("5\n"); break;
case 4: printf("7\n"); break;
default: printf("n\n"); break;
}

return 0;

}