highway.cpp: In function 'void subtree(int, std::vector<int>, std::vector<int>, int, int, int)':
highway.cpp:24:9: error: declaration of 'int a' shadows a parameter
24 | int a=u[ans];
| ^
highway.cpp:10:50: note: 'int a' previously declared here
10 | void subtree(int n,vector<int>u,vector<int>v,int a,int b,int cost){
| ~~~~^
highway.cpp:25:9: error: declaration of 'int b' shadows a parameter
25 | int b=v[ans];
| ^
highway.cpp:10:56: note: 'int b' previously declared here
10 | void subtree(int n,vector<int>u,vector<int>v,int a,int b,int cost){
| ~~~~^
highway.cpp: In function 'void find_pair(int, std::vector<int>, std::vector<int>, int, int)':
highway.cpp:71:16: warning: comparison of integer expressions of different signedness: 'std::vector<int>::size_type' {aka 'long unsigned int'} and 'int' [-Wsign-compare]
71 | if(U.size()!=N-1)return answer(rand()%N,rand()%N);
| ~~~~~~~~^~~~~