Compilare: user.cpp: In function ‘int main()’: user.cpp:38:37: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int i = 0; i < sortop.size(); i++) { ^ user.cpp:57:11: warning: statement has no effect [-Wunused-value] for (i; i >= 0; i--) { ^ user.cpp:18:18: warning: unused variable ‘c’ [-Wunused-variable] int n, a, b, c; ^