Compilare: main.cpp: In function 'int main()': main.cpp:12:19: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i=0; i<s.size(); i++) { ~^~~~~~~~~ main.cpp:18:19: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i=0; i<s.size(); i++) { ~^~~~~~~~~ main.cpp:45:17: warning: variable 'tmp' set but not used [-Wunused-but-set-variable] int tmp=0; ^~~