Compilare: user.cpp: In function ‘void df(int, int, int)’: user.cpp:18:9: warning: unused variable ‘i’ [-Wunused-variable] int i, l = ls[x].size(), y; ^ user.cpp:18:12: warning: unused variable ‘l’ [-Wunused-variable] int i, l = ls[x].size(), y; ^ user.cpp: In function ‘int main()’: user.cpp:43:32: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("lca.in","r",stdin); ^ user.cpp:44:34: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("lca.out","w",stdout); ^ user.cpp:45:28: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d %d\n", &n,&m); ^ user.cpp:47:29: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d ", &tt[i]); ^ user.cpp:52:31: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d %d\n",&x,&y); ^