books.cpp: In function 'll minimum_walk(std::vector<int>, int)':
books.cpp:34:19: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<std::pair<int, int> >::size_type' {aka 'long unsigned int'} [-Wsign-compare]
34 | for(int i = 0; i < sz(range);) {
| ^
books.cpp:36:11: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<std::pair<int, int> >::size_type' {aka 'long unsigned int'} [-Wsign-compare]
36 | while(j < sz(range) and range[j].fr < r) {
| ^
books.cpp:44:17: warning: 'ans' may be used uninitialized in this function [-Wmaybe-uninitialized]
44 | return ans + 2*L;
| ^