Compilare: user.cpp: In function ‘int main()’: user.cpp:31:9: warning: unused variable ‘i’ [-Wunused-variable] int i,n1,n2; ^ user.cpp:32:36: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("arbore7.in","r",stdin); ^ user.cpp:33:38: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("arbore7.out","w",stdout); ^ user.cpp:34:19: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d",&n); ^ user.cpp:38:30: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d%d",&n1,&n2); ^