Compilare: main.cpp: In function 'int main()': main.cpp:40:23: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i = 0 ; i < s.size() ; i++) ~~^~~~~~~~~~ main.cpp:95:23: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i = 0 ; i < expr.size() ; i++) ~~^~~~~~~~~~~~~ main.cpp:99:31: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int k = 0 ; k < v.size() ; k++) ~~^~~~~~~~~~