Compilare: main.cpp: In function 'void backt(int, int, int, std::__cxx11::string, std::__cxx11::string, int (*)[8])': main.cpp:13:33: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] if ((a <= n || b <= n) && p >= v.size()) ~~^~~~~~~~~~~ main.cpp:32:18: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] while (p < v.size()) { ~~^~~~~~~~~~ main.cpp:44:26: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] if (s.size() == n && s > last) { ~~~~~~~~~^~~~ main.cpp:58:18: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] while (p < v.size()) { ~~^~~~~~~~~~ main.cpp:70:26: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] if (s.size() == n && s > last) { ~~~~~~~~~^~~~ main.cpp:84:18: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] while (p < v.size()) { ~~^~~~~~~~~~ main.cpp:96:26: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] if (s.size() == n && s > last) { ~~~~~~~~~^~~~ main.cpp:110:18: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] while (p < v.size()) { ~~^~~~~~~~~~ main.cpp:122:26: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] if (s.size() == n && s > last) { ~~~~~~~~~^~~~