Compilare: main.cpp: In instantiation of 'Range_minimum_query<T>::Range_minimum_query(std::vector<std::vector<T> >&) [with T = int]': main.cpp:75:35: required from here main.cpp:21:23: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int i = 0; i < arr.size(); i++) { main.cpp:22:27: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int j = 0; j < arr.size(); j++) { main.cpp:27:30: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int k = 1; (1 << k) <= arr.size(); k++) { main.cpp:28:27: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int i = 1; i <= arr.size() - (1 << k)+1; i++) { ~~^~~~~~~~~~~~~~~~~~~~~~~~~~ main.cpp:29:31: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int j = 1; j <= arr.size() - (1 << k)+1; j++) { ~~^~~~~~~~~~~~~~~~~~~~~~~~~~ main.cpp:30:100: warning: suggest parentheses around '-' inside '<<' [-Wparentheses] lookup[k][i][j] = std::max(std::max(lookup[k - 1][i][j], lookup[k - 1][i + (1 << k - 1)][j]), ~~^~~ main.cpp:31:82: warning: suggest parentheses around '-' inside '<<' [-Wparentheses] std::max(lookup[k - 1][i][j + (1 << k - 1)], ~~^~~ main.cpp:32:79: warning: suggest parentheses around '-' inside '<<' [-Wparentheses] lookup[k - 1][i + (1 << k - 1)][j + (1 << k - 1)])); ~~^~~ main.cpp:32:97: warning: suggest parentheses around '-' inside '<<' [-Wparentheses] lookup[k - 1][i + (1 << k - 1)][j + (1 << k - 1)])); ~~^~~ main.cpp:39:23: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int i = 2; i < arr.size(); i++) {