Compilare: user.cpp: In function ‘int main()’: user.cpp:49:20: warning: statement has no effect [-Wunused-value] last_value - v[i]; ^ user.cpp:16:27: warning: ignoring return value of ‘int fscanf(FILE*, const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] fscanf(f,"%d%d",&n,&k); ^ user.cpp:19:29: warning: ignoring return value of ‘int fscanf(FILE*, const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] fscanf(f,"%d",&v[i]); ^