Compilare: user.cpp: In function ‘bool ok(int)’: user.cpp:44:44: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int j = len ; j < sir[i].size() ; ++j) { ^ user.cpp:66:44: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int j = len ; j < sir[n - 1].size() ; ++j) { ^ user.cpp: In function ‘int main()’: user.cpp:90:29: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] if (sir[i].size() < minsz) ^