/in/foo.c: In function 'main':
/in/foo.c:7:17: warning: passing argument 2 of 'Troitsky' from incompatible pointer type [-Wincompatible-pointer-types]
  key=Troitsky(n,a);
                 ^
/in/foo.c:2:5: note: expected 'long int *' but argument is of type 'int *'
 int Troitsky(int n, long a[]);
     ^~~~~~~~