Compilare: user.cpp: In function ‘int main()’: user.cpp:79:20: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] if(ans.size() != N) {printf("-1\n"); return 0;} ^ user.cpp:11:47: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] int N, Na, Nb; scanf("%d%d%d", &N, &Na, &Nb); ^ user.cpp:15:22: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d", &itr); ^ user.cpp:18:22: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d", &itr); ^