Compilare: user.cpp: In function ‘int main()’: user.cpp:11:32: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen ("ec.in","r",stdin); ^ user.cpp:12:34: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen ("ec.out","w",stdout); ^ user.cpp:13:28: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf ("%d %d", &n, &k); ^ user.cpp:17:29: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf ("%d", &x); ^ user.cpp:20:17: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf ("\n"); ^ user.cpp:27:16: warning: ignoring return value of ‘char* gets(char*)’, declared with attribute warn_unused_result [-Wunused-result] gets(a); ^ /tmp/cc5jlYeP.o: In function `main': user.cpp:(.text.startup+0x130): warning: the `gets' function is dangerous and should not be used.