Compilare: main.cpp: In function 'void getGrade(int, int)': main.cpp:20:22: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i = 0; i < v[node].size() ; i ++){ ~~^~~~~~~~~~~~~~~~ main.cpp: In function 'int main()': main.cpp:27:39: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)', declared with attribute warn_unused_result [-Wunused-result] freopen("tairos.in" , "r" , stdin); ^ main.cpp:28:40: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)', declared with attribute warn_unused_result [-Wunused-result] freopen("tairos.out", "w" , stdout); ^ main.cpp:29:28: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result] scanf("%d%d" , &n , &d); ^ main.cpp:32:32: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result] scanf("%d%d" , &x , &y); ^