foo.c:4:6: warning: return type of 'main' is not 'int' [-Wmain]
 void main()
      ^~~~
foo.c: In function 'insert':
foo.c:20:2: warning: statement with no effect [-Wunused-value]
  for(i;i<n;i++)
  ^~~
foo.c: In function 'output':
foo.c:38:2: warning: statement with no effect [-Wunused-value]
  for(i;i<n+1;i++)
  ^~~
foo.c: In function 'main':
foo.c:7:9: warning: ignoring return value of 'scanf', declared with attribute warn_unused_result [-Wunused-result]
  int n; scanf("%d",&n);
         ^~~~~~~~~~~~~~
foo.c:10:3: warning: ignoring return value of 'scanf', declared with attribute warn_unused_result [-Wunused-result]
   scanf("%d",&a[i]);
   ^~~~~~~~~~~~~~~~~
foo.c:12:9: warning: ignoring return value of 'scanf', declared with attribute warn_unused_result [-Wunused-result]
  int x; scanf("%d",&x);
         ^~~~~~~~~~~~~~
foo.c: In function 'insert':
foo.c:18:6: warning: 'j' may be used uninitialized in this function [-Wmaybe-uninitialized]
  int j;
      ^

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