Compilare: main.cpp: In function 'int main()': main.cpp:26:10: warning: statement has no effect [-Wunused-value] for (i ; i <= 2 * n ; ++ i) { ^ main.cpp:17:32: warning: ignoring return value of 'int fscanf(FILE*, const char*, ...)', declared with attribute warn_unused_result [-Wunused-result] int n ; fscanf(in, "%d", &n) ; ^ main.cpp:21:28: warning: ignoring return value of 'int fscanf(FILE*, const char*, ...)', declared with attribute warn_unused_result [-Wunused-result] fscanf(in, "%d", &val) ; ^ main.cpp:27:28: warning: ignoring return value of 'int fscanf(FILE*, const char*, ...)', declared with attribute warn_unused_result [-Wunused-result] fscanf(in, "%d", &val) ; ^