optim.cpp: In function 'int main()': optim.cpp:77: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)', declared with attribute warn_unused_result optim.cpp:78: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)', declared with attribute warn_unused_result optim.cpp:79: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result optim.cpp:80: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result optim.cpp:82: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result