Compilare: main.cpp: In function 'int main()': main.cpp:58:28: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int i=1; i<v.size()-1; ++i) ~^~~~~~~~~~~ main.cpp:61:28: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int i=1; i<v.size()-1;) { ~^~~~~~~~~~~ main.cpp:75:24: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int i=1; i<v.size()-1; ++i) ~^~~~~~~~~~~ main.cpp:25:13: warning: 'last' may be used uninitialized in this function [-Wmaybe-uninitialized] if (x != last) ^~