Compilare: main.cpp: In function 'int main()': main.cpp:22:24: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i = 0; i < s.size(); i++) { ~~^~~~~~~~~~ main.cpp:32:24: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i = 0; i < s.size(); i++) { ~~^~~~~~~~~~ main.cpp:21:15: warning: variable 'y' set but not used [-Wunused-but-set-variable] char x, y; ^