foo.c:3:1: error: unknown type name 'using'
    3 | using namespace std;
      | ^~~~~
foo.c:3:17: error: expected '=', ',', ';', 'asm' or '__attribute__' before 'std'
    3 | using namespace std;
      |                 ^~~
foo.c:16:1: warning: return type defaults to 'int' [-Wimplicit-int]
   16 | main()
      | ^~~~
foo.c: In function 'main':
foo.c:18:2: warning: ignoring return value of 'scanf', declared with attribute warn_unused_result [-Wunused-result]
   18 |  scanf("%lld",&n);
      |  ^~~~~~~~~~~~~~~~
foo.c:21:3: warning: ignoring return value of 'scanf', declared with attribute warn_unused_result [-Wunused-result]
   21 |   scanf("%lld %lld",&f[i].a,&f[i].b);
      |   ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

Found 10 testcases.
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