traseu3.cpp: In function 'void read()': traseu3.cpp:10: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)', declared with attribute warn_unused_result traseu3.cpp:11: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result traseu3.cpp:13: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result traseu3.cpp: In function 'int main()': traseu3.cpp:61: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)', declared with attribute warn_unused_result