Compilare: user.cpp: In function ‘int main()’: user.cpp:33:34: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen ("spirt.in", "r", stdin); ^ user.cpp:34:36: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen ("spirt.out", "w", stdout); ^ user.cpp:36:26: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf ("%d%d\n", &N, &M); ^ user.cpp:37:14: warning: ignoring return value of ‘char* gets(char*)’, declared with attribute warn_unused_result [-Wunused-result] gets (x + 1); ^ /tmp/cc229wV9.o: In function `main': user.cpp:(.text.startup+0x70): warning: the `gets' function is dangerous and should not be used.