cerc.cpp: In function 'void update(int)': cerc.cpp:10: warning: statement has no effect cerc.cpp: In function 'int query(int)': cerc.cpp:15: warning: statement has no effect cerc.cpp: In function 'int main()': cerc.cpp:20: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)', declared with attribute warn_unused_result cerc.cpp:21: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)', declared with attribute warn_unused_result cerc.cpp:23: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result cerc.cpp:25: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result