trapez.cpp: In function 'int main()': trapez.cpp:101: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)', declared with attribute warn_unused_result trapez.cpp:102: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)', declared with attribute warn_unused_result trapez.cpp:103: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result