/in/foo.c: In function 'main':
/in/foo.c:6:16: warning: implicit declaration of function 'scamf' [-Wimplicit-function-declaration]
  int n1,n2,n3; scamf("%d%d%d",&n1,&n2,&n3);
                ^~~~~
/in/foo.c:8:11: warning: format '%d' expects argument of type 'int *', but argument 2 has type 'int' [-Wformat=]
   scanf("%d",a1[i]);
           ^
/in/foo.c:10:11: warning: format '%d' expects argument of type 'int *', but argument 2 has type 'int' [-Wformat=]
   scanf("%d",a2[i]);
           ^
/in/foo.c:12:11: warning: format '%d' expects argument of type 'int *', but argument 2 has type 'int' [-Wformat=]
   scanf("%d",a3[i]);
           ^
/in/foo.c:13:5: warning: implicit declaration of function 'SetUnion' [-Wimplicit-function-declaration]
     SetUnion(a1,a2);
     ^~~~~~~~
/in/foo.c:15:2: error: too few arguments to function 'Output'
  Output();
  ^~~~~~
/in/foo.c:2:6: note: declared here
 void Output(int a[],int n);
      ^~~~~~
/in/foo.c:16:2: error: too few arguments to function 'Output'
  Output();
  ^~~~~~
/in/foo.c:2:6: note: declared here
 void Output(int a[],int n);
      ^~~~~~
/in/foo.c: At top level:
/in/foo.c:18:6: warning: conflicting types for 'SetUnion'
 void SetUnion()
      ^~~~~~~~
/in/foo.c:13:5: note: previous implicit declaration of 'SetUnion' was here
     SetUnion(a1,a2);
     ^~~~~~~~