Compilare: user.cpp: In function ‘void DF(int)’: user.cpp:9:9: warning: unused variable ‘i’ [-Wunused-variable] int i,k; ^ user.cpp:9:11: warning: unused variable ‘k’ [-Wunused-variable] int i,k; ^ user.cpp: In function ‘int main()’: user.cpp:20:32: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("dfs.in","r",stdin); ^ user.cpp:21:34: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("dfs.out","w",stdout); ^ user.cpp:22:25: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d %d",&n,&m); ^ user.cpp:25:29: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d %d",&x,&y); ^