Compilare: main.cpp: In function 'int main()': main.cpp:15:22: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i=0;i<c.size();i++){ ~^~~~~~~~~ main.cpp:28:22: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i=0;i<s.size();i++){ ~^~~~~~~~~ main.cpp:27:14: warning: unused variable 'ok' [-Wunused-variable] bool ok=0; ^~