Compilare: main.cpp: In function 'void build()': main.cpp:56:23: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int i = 2; i <= line.size(); ++i) ~~^~~~~~~~~~~~~~ main.cpp:59:23: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int i = 0; i < line.size(); ++i) ~~^~~~~~~~~~~~~ main.cpp:62:30: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int i = 1; (1 << i) < line.size(); ++i) ~~~~~~~~~^~~~~~~~~~~~~ main.cpp:63:42: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int j = 0; j + (1 << i) - 1 < line.size(); ++j) ~~~~~~~~~~~~~~~~~^~~~~~~~~~~~~