train.cpp:17:5: error: ambiguating new declaration of 'int who_wins(std::vector<int>, std::vector<int>, std::vector<int>, std::vector<int>)'
17 | int who_wins(vector<int>o, vector<int>p, vector<int>u, vector<int>v){
| ^~~~~~~~
In file included from train.cpp:2:
train.h:3:18: note: old declaration 'std::vector<int> who_wins(std::vector<int>, std::vector<int>, std::vector<int>, std::vector<int>)'
3 | std::vector<int> who_wins(std::vector<int> a, std::vector<int> r, std::vector<int> u, std::vector<int> v);
| ^~~~~~~~
train.cpp: In function 'int who_wins(std::vector<int>, std::vector<int>, std::vector<int>, std::vector<int>)':
train.cpp:33:9: error: cannot convert 'std::vector<int>' to 'int' in return
33 | return ans;
| ^~~