Compilare: user.c: In function ‘f’: user.c:3:19: warning: suggest parentheses around arithmetic in operand of ‘|’ [-Wparentheses] return x+y ? y&1|x*2&2|4*f(x/2,y/2) : 0; ^ user.c: In function ‘main’: user.c:7:12: warning: ignoring return value of ‘freopen’, declared with attribute warn_unused_result [-Wunused-result] freopen("z.in","r", stdin); ^ user.c:8:12: warning: ignoring return value of ‘freopen’, declared with attribute warn_unused_result [-Wunused-result] freopen("z.out","w",stdout); ^ user.c:9:23: warning: ignoring return value of ‘scanf’, declared with attribute warn_unused_result [-Wunused-result] int n,k,x,y; scanf("%d%d",&n,&k); ^ user.c:11:14: warning: ignoring return value of ‘scanf’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d%d",&x,&y); ^