foo.cc: In function 'void search(int, int)':
foo.cc:17:15: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   17 |  for(int i=0;i<rc[x].size();i++){
      |              ~^~~~~~~~~~~~~
foo.cc: In function 'int main()':
foo.cc:25:7: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
   25 |  scanf("%d%d%d",&K,&V,&n);
      |  ~~~~~^~~~~~~~~~~~~~~~~~~
foo.cc:27:8: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
   27 |   scanf("%d%d",&v[i],&w[i]);
      |   ~~~~~^~~~~~~~~~~~~~~~~~~~

[Hydro](https://hydro.ac)提供评测服务