kdtree.cpp: In function 'void DFS(int, int)': kdtree.cpp:12: warning: comparison between signed and unsigned integer expressions kdtree.cpp: In function 'int main()': kdtree.cpp:32: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)', declared with attribute warn_unused_result kdtree.cpp:33: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)', declared with attribute warn_unused_result kdtree.cpp:35: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result kdtree.cpp:37: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result