rack.cpp:12:1: warning: ISO C++ forbids declaration of 'main' with no type [-Wreturn-type]
12 | main (){
| ^~~~
rack.cpp: In function 'int main()':
rack.cpp:27:18: warning: comparison of integer expressions of different signedness: 'long long int' and 'std::vector<long long int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
27 | while(id < v.size() && v[id] + a <= (1<<n) && !f[v[id] + a]){
| ~~~^~~~~~~~~~
rack.cpp:30:26: warning: comparison of integer expressions of different signedness: 'std::vector<long long int>::size_type' {aka 'long unsigned int'} and 'long long int' [-Wsign-compare]
30 | if (v.size() == k) {
| ~~~~~~~~~^~~~