Compilare: main.cpp: In function 'void build(std::vector<int>)': main.cpp:12:23: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare] 12 | for (int i = 0; i < a.size(); i++) { | ~~^~~~~~~~~~ main.cpp:17:38: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare] 17 | for (int i = 0; i + (1 << j) <= a.size(); i++) { | ~~~~~~~~~~~~~^~~~~~~~~~~