Compilare: user.cpp: In function ‘bool ok(int)’: user.cpp:18:11: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] if (l > v[i].size()) ~~^~~~~~~~~~~~~ user.cpp:23:23: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int j = l; j < v[i].size(); j++) { ~~^~~~~~~~~~~~~ user.cpp:14:8: warning: unused variable ‘k’ [-Wunused-variable] bool k; ^ user.cpp: In function ‘int main()’: user.cpp:56:14: warning: ‘sol’ may be used uninitialized in this function [-Wmaybe-uninitialized] fout << sol; ^