Compilare: user.cpp: In function ‘int main()’: user.cpp:47:33: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("fpwl.in", "r", stdin); ^ user.cpp:48:35: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("fpwl.out", "w", stdout); ^ user.cpp:51:24: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d%d", &n, &k); ^ user.cpp:53:25: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d", val + i); ^ user.cpp:55:13: warning: ignoring return value of ‘char* gets(char*)’, declared with attribute warn_unused_result [-Wunused-result] gets(sign); gets(sign); ^ user.cpp:55:25: warning: ignoring return value of ‘char* gets(char*)’, declared with attribute warn_unused_result [-Wunused-result] gets(sign); gets(sign); ^ /tmp/ccRNjjnj.o: In function `main': user.cpp:(.text.startup+0xa3): warning: the `gets' function is dangerous and should not be used.