Compilare: main.cpp: In function 'bool ok(int, int)': main.cpp:19:14: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] while (a < v[x].size() && b < v[y].size()) { ~~^~~~~~~~~~~~~ main.cpp:19:33: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] while (a < v[x].size() && b < v[y].size()) { ~~^~~~~~~~~~~~~ main.cpp: In function 'int main()': main.cpp:66:27: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int j = 0; j < s.size(); ++j) { ~~^~~~~~~~~~ main.cpp:69:34: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] if (s[j] == ' ' || j == s.size() - 1) { ~~^~~~~~~~~~~~~~~ main.cpp:91:27: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int z = 0; z < v[pos].size(); ++z) { ~~^~~~~~~~~~~~~~~ main.cpp:106:39: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int z = 0; z < v[j].size(); ++z) { ~~^~~~~~~~~~~~~