Compilare: user.cpp: In function ‘int main()’: user.cpp:37:39: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("ratina.in","r",stdin); ^ user.cpp:38:41: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("ratina.out","w",stdout); ^ user.cpp:40:32: 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:43:44: warning: ignoring return value of ‘char* gets(char*)’, declared with attribute warn_unused_result [-Wunused-result] gets(S), v[i].x = S, v[i].y = i; ^ /tmp/cckj9Ahi.o: In function `main': user.cpp:(.text.startup+0x90): warning: the `gets' function is dangerous and should not be used.