/in/foo.c: In function 'main':
/in/foo.c:7:14: warning: implicit declaration of function 'malloc' [-Wimplicit-function-declaration]
  pi = (int *)malloc(n * sizeof(int));
              ^
/in/foo.c:7:14: warning: incompatible implicit declaration of built-in function 'malloc'
/in/foo.c:7:14: note: include '<stdlib.h>' or provide a declaration of 'malloc'
/in/foo.c:6:2: warning: ignoring return value of 'scanf', declared with attribute warn_unused_result [-Wunused-result]
  scanf("%d", &n);
  ^
/in/foo.c:11:3: warning: ignoring return value of 'scanf', declared with attribute warn_unused_result [-Wunused-result]
   scanf("%d", &pi[i]);
   ^