Compilare: user.cpp: In function ‘int main()’: user.cpp:57:39: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("showroom.in", "r", stdin); ^ user.cpp:58:41: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("showroom.out", "w", stdout); ^ user.cpp:61:20: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d", &N); ^ user.cpp:62:34: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d%d%d\n", &a, &r, &k); ^ user.cpp:68:20: warning: ignoring return value of ‘char* gets(char*)’, declared with attribute warn_unused_result [-Wunused-result] gets(s + 1); ^ /tmp/ccdySRe8.o: In function `main': user.cpp:(.text.startup+0xbf): warning: the `gets' function is dangerous and should not be used.