Compilare: user.cpp: In function ‘int main()’: user.cpp:99:33: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("comp.in","r",stdin); ^ user.cpp:100:35: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("comp.out","w",stdout); ^ user.cpp:102:19: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d",&n); ^ user.cpp:104:28: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d%d",&a,&b); ^ user.cpp: In function ‘void DFS(int)’: user.cpp:27:26: warning: ‘which’ may be used uninitialized in this function [-Wmaybe-uninitialized] color[node]=which; ^