Compilare: user.cpp: In function ‘int main()’: user.cpp:28:25: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i=a; i<=b; ++i) ^ user.cpp:27:13: warning: unused variable ‘x’ [-Wunused-variable] int x, s; ^ user.cpp:27:16: warning: unused variable ‘s’ [-Wunused-variable] int x, s; ^