foo.cc: In function 'void dfs(int, int, int)':
foo.cc:26:36: warning: format '%d' expects argument of type 'int', but argument 2 has type 'std::vector<int>::size_type {aka long unsigned int}' [-Wformat=]
             printf("%d", vec.size());
                          ~~~~~~~~~~^
foo.cc: In function 'int main()':
foo.cc:42:10: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
     scanf("%d%d", &q, &n);
     ~~~~~^~~~~~~~~~~~~~~~
foo.cc:44:14: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
         scanf("%d", a + i);
         ~~~~~^~~~~~~~~~~~~

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