Compilare: main.cpp: In function 'std::vector<int> MergeVectors(std::vector<int>, std::vector<int>)': main.cpp:57:23: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int i = 0; i < a.size(); i++) { ~~^~~~~~~~~~ main.cpp: In function 'std::vector<int> IntersectVectors(std::vector<int>, std::vector<int>)': main.cpp:73:23: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int i = 1; i < a.size(); i++) { ~~^~~~~~~~~~ main.cpp: In function 'std::vector<int> f1()': main.cpp:91:35: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] while (s[i] == '+' && (i + 1) < s.size()) { ~~~~~~~~^~~~~~~~~~ main.cpp: In function 'std::vector<int> f2()': main.cpp:106:35: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] while (s[i] == '*' && (i + 1) < s.size()) { ~~~~~~~~^~~~~~~~~~ main.cpp: In function 'std::vector<int> f3()': main.cpp:124:16: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] else if (i < s.size() && (s[i] >= 'A' && s[i] <= 'Z')) { ~~^~~~~~~~~~ main.cpp:129:1: warning: control reaches end of non-void function [-Wreturn-type] } ^