Compilare: user.cpp: In function ‘int main()’: user.cpp:12:15: warning: unused variable ‘a’ [-Wunused-variable] int n, q, a, b; ^ user.cpp:12:18: warning: unused variable ‘b’ [-Wunused-variable] int n, q, a, b; ^ user.cpp:15:9: warning: variable ‘fr’ set but not used [-Wunused-but-set-variable] int fr[MAXN] = {0}; ^