Compilare: main.cpp: In function 'int main()': main.cpp:23:23: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(i = 0 ; i < s.size() ; i++) ~~^~~~~~~~~~ main.cpp:26:23: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(i = 0 ; i < s.size() ; i++) ~~^~~~~~~~~~ main.cpp:38:23: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(i = 0 ; i < s.size() ; i++) ~~^~~~~~~~~~ main.cpp:41:23: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(i = 0 ; i < s.size() ; i++) ~~^~~~~~~~~~