ech.cpp: In function 'int main()': ech.cpp:37: warning: unused variable 'n' ech.cpp:35: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)', declared with attribute warn_unused_result ech.cpp:36: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)', declared with attribute warn_unused_result ech.cpp:38: warning: ignoring return value of 'char* gets(char*)', declared with attribute warn_unused_result /tmp/cc4priVl.o: In function `main': ech.cpp:(.text+0x17b): warning: the `gets' function is dangerous and should not be used.