Compilare: main.cpp: In function 'std::vector<int> Merge(std::vector<int>, std::vector<int>)': main.cpp:52:16: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] if (i1 == a.size() && i2 == b.size()) return toReturn; ~~~^~~~~~~~~~~ main.cpp:52:34: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] if (i1 == a.size() && i2 == b.size()) return toReturn; ~~~^~~~~~~~~~~ main.cpp:53:21: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] else if (i1 == a.size()) toReturn.push_back(b[i2++]); ~~~^~~~~~~~~~~ main.cpp:54:21: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] else if (i2 == b.size()) toReturn.push_back(a[i1++]); ~~~^~~~~~~~~~~ main.cpp: In function 'std::vector<int> MergeVectors(std::vector<int>, std::vector<int>)': main.cpp:66:23: 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:77:23: 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:95:35: 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:110:35: 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:128:16: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] else if (i < s.size() && (s[i] >= 'A' && s[i] <= 'Z')) { ~~^~~~~~~~~~ main.cpp:133:1: warning: control reaches end of non-void function [-Wreturn-type] } ^