Compilare: user.cpp: In function ‘int main()’: user.cpp:29:14: warning: left operand of comma operator has no effect [-Wunused-value] int w=(n,m); ^ user.cpp:15:26: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen(IN,"r",stdin); ^ user.cpp:16:28: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen(OUT,"w",stdout); ^ user.cpp:17:14: warning: ignoring return value of ‘char* gets(char*)’, declared with attribute warn_unused_result [-Wunused-result] gets(sir); ^ user.cpp:18:14: warning: ignoring return value of ‘char* gets(char*)’, declared with attribute warn_unused_result [-Wunused-result] gets(per); ^ /tmp/ccADxV4k.o: In function `main': user.cpp:(.text.startup+0x6d): warning: the `gets' function is dangerous and should not be used.