Compilare: user.cpp: In member function ‘int Trie::length_com_pref(int, int*, int)’: user.cpp:67:54: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int i = 0;i < vec[mid][s[id][mid] - 'a'].size();++i) ^ user.cpp:59:8: warning: unused variable ‘q’ [-Wunused-variable] Node *q = t; ^ user.cpp: In function ‘int main()’: user.cpp:109:10: warning: unused variable ‘f’ [-Wunused-variable] int e, f; ^ user.cpp:93:6: warning: unused variable ‘op’ [-Wunused-variable] int op; ^ user.cpp:100:28: warning: ignoring return value of ‘int fscanf(FILE*, const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] fscanf(in, "%d%d", &N, &K); ^ user.cpp:103:25: warning: ignoring return value of ‘int fscanf(FILE*, const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] fscanf(in, "%s", s[i]); ^ user.cpp:110:23: warning: ignoring return value of ‘int fscanf(FILE*, const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] fscanf(in, "%d", &e); ^ user.cpp:113:27: warning: ignoring return value of ‘int fscanf(FILE*, const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] fscanf(in, "%d", &t[j]); ^