optim.cpp: In function 'void afis()': optim.cpp:54: warning: comparison between signed and unsigned integer expressions optim.cpp: In function 'int main()': optim.cpp:95: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)', declared with attribute warn_unused_result optim.cpp:96: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)', declared with attribute warn_unused_result optim.cpp:97: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result optim.cpp:100: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result