Compilare: user.cpp: In function ‘int main()’: user.cpp:83:25: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] if (sol.size() != N / 2) { ^ user.cpp:72:24: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d%d", &N, &M); ^ user.cpp:75:26: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d%d", &a, &b); ^