books.cpp: In function 'long long int minimum_walk(std::vector<int>, int)':
books.cpp:4:40: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
    4 | #define rep(i,a,b) for (int i = (a); i < (b); i++)
      |                                        ^
books.cpp:20:2: note: in expansion of macro 'rep'
   20 |  rep(i,0,p.size())
      |  ^~~
books.cpp:4:40: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
    4 | #define rep(i,a,b) for (int i = (a); i < (b); i++)
      |                                        ^
books.cpp:53:3: note: in expansion of macro 'rep'
   53 |   rep(i,0,cycle.size())
      |   ^~~
books.cpp:51:7: warning: unused variable 'low' [-Wunused-variable]
   51 |   int low = 0, high = 0; // inc
      |       ^~~
books.cpp:52:7: warning: unused variable 'ind' [-Wunused-variable]
   52 |   int ind = 0;
      |       ^~~