patrate5.cpp: In function 'void read()': patrate5.cpp:27: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)', declared with attribute warn_unused_result patrate5.cpp:28: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result patrate5.cpp:32: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result patrate5.cpp: In function 'void write()': patrate5.cpp:118: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)', declared with attribute warn_unused_result In file included from /usr/include/string.h:640, from /usr/include/c++/4.4/cstring:45, from patrate5.cpp:3: In function 'void* memcpy(void*, const void*, size_t)', inlined from 'int Ok(int, int)' at patrate5.cpp:97: /usr/include/bits/string3.h:52: warning: call to void* __builtin___memcpy_chk(void*, const void*, unsigned int, unsigned int) will always overflow destination buffer