foo.cc: In function 'int main()':
foo.cc:53:2: warning: this 'for' clause does not guard... [-Wmisleading-indentation]
  for(int i=0;i<n1;i++)
  ^~~
foo.cc:55:3: note: ...this statement, but the latter is misleadingly indented as if it were guarded by the 'for'
   printf("\n");
   ^~~~~~
foo.cc:46:7: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
  scanf("%d %d",&n1,&n2);
  ~~~~~^~~~~~~~~~~~~~~~~
foo.cc:48:8: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
   scanf("%d",&a1[i]);
   ~~~~~^~~~~~~~~~~~~
foo.cc:50:8: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
   scanf("%d",&a2[i]);
   ~~~~~^~~~~~~~~~~~~

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