foo.cc: In function 'int main()':
foo.cc:21:8: warning: unused variable 'j' [-Wunused-variable]
  int i,j;
        ^
foo.cc:22:7: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
  scanf("%d",&n);
  ~~~~~^~~~~~~~~
foo.cc:24:8: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
   scanf("%d%d",&a[i].l,&a[i].r);
   ~~~~~^~~~~~~~~~~~~~~~~~~~~~~~

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