Compilare: user.cpp: In function ‘long long int read()’: user.cpp:29:22: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] while(p < s.size() && isdigit(s[p])) { ^ user.cpp: In function ‘int eval1()’: user.cpp:51:31: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i = 0; i < R.size(); i++) { ^ user.cpp: In function ‘std::vector<int> expr()’: user.cpp:76:22: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] while(p < s.size() && s[p] != ')' && s[p] != ']') { ^ user.cpp: In function ‘int main()’: user.cpp:102:31: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i = 0; i < R.size(); i++) { ^