Compilare: main.cpp: In function 'int main()': main.cpp:109:26: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for ( int i = 0 ; i < a [id] .size () ; i ++ ) { ~~^~~~~~~~~~~~~~~~~ main.cpp:51:34: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)', declared with attribute warn_unused_result [-Wunused-result] freopen("arbore.in", "r", stdin); ^ main.cpp:52:36: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)', declared with attribute warn_unused_result [-Wunused-result] freopen("arbore.out", "w", stdout); ^ main.cpp:60:23: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result] scanf("%d%d",&a,&b) ; ^ main.cpp:71:37: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result] scanf("%d%d",&node,&x) , node -- ; ^ main.cpp:103:20: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result] scanf ("%d",&x) ; ^