foo.c: In function 'main':
foo.c:11:11: warning: format '%d' expects argument of type 'int *', but argument 2 has type 'int' [-Wformat=]
   scanf("%d",a1[i]);
          ~^  ~~~~~
foo.c:13:11: warning: format '%d' expects argument of type 'int *', but argument 2 has type 'int' [-Wformat=]
   scanf("%d",a2[i]);
          ~^  ~~~~~
foo.c:15:11: warning: format '%d' expects argument of type 'int *', but argument 2 has type 'int' [-Wformat=]
   scanf("%d",a3[i]);
          ~^  ~~~~~
foo.c: In function 'Merge':
foo.c:25:18: error: 'i' undeclared (first use in this function)
   printf("%d ",b[i]);
                  ^
foo.c:25:18: note: each undeclared identifier is reported only once for each function it appears in
foo.c: In function 'main':
foo.c:8:2: warning: ignoring return value of 'scanf', declared with attribute warn_unused_result [-Wunused-result]
  scanf("%d%d%d",&n1,&n2,&n3);
  ^~~~~~~~~~~~~~~~~~~~~~~~~~~
foo.c:11:3: warning: ignoring return value of 'scanf', declared with attribute warn_unused_result [-Wunused-result]
   scanf("%d",a1[i]);
   ^~~~~~~~~~~~~~~~~
foo.c:13:3: warning: ignoring return value of 'scanf', declared with attribute warn_unused_result [-Wunused-result]
   scanf("%d",a2[i]);
   ^~~~~~~~~~~~~~~~~
foo.c:15:3: warning: ignoring return value of 'scanf', declared with attribute warn_unused_result [-Wunused-result]
   scanf("%d",a3[i]);
   ^~~~~~~~~~~~~~~~~

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