atac.cpp: In function 'int main()': atac.cpp:47: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)', declared with attribute warn_unused_result atac.cpp:48: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)', declared with attribute warn_unused_result atac.cpp:51: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result atac.cpp:54: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result atac.cpp:82: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result atac.cpp:85: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result atac.cpp:49: warning: 'last' may be used uninitialized in this function