Compilare: user.cpp: In function ‘void insert(int)’: user.cpp:121:13: warning: unused variable ‘J’ [-Wunused-variable] int J = 0; ^ user.cpp: In function ‘int main()’: user.cpp:218:24: warning: ignoring return value of ‘int fscanf(FILE*, const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] fscanf(f, "%d", &N); ^ user.cpp:224:37: warning: ignoring return value of ‘int fscanf(FILE*, const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] fscanf(f, "%d %d", &tip, &x); ^