Compilare: user.cpp: In function ‘int main()’: user.cpp:54:33: 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:55:35: 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:57:26: 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:59:15: warning: ignoring return value of ‘char* gets(char*)’, declared with attribute warn_unused_result [-Wunused-result] gets (sir + 1); ^ /tmp/ccY8I1Y7.o: In function `main': user.cpp:(.text.startup+0x82): warning: the `gets' function is dangerous and should not be used.