Compilare: user.cpp: In function ‘int main()’: user.cpp:129:37: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("namlei.in", "r", stdin); ^ user.cpp:130:39: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("namlei.out", "w", stdout); ^ user.cpp:135:43: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d %d %d %d\n", &n, &k, &x, &y); ^ user.cpp:137:19: warning: ignoring return value of ‘char* gets(char*)’, declared with attribute warn_unused_result [-Wunused-result] gets(buff); ^ user.cpp:147:19: warning: ignoring return value of ‘char* gets(char*)’, declared with attribute warn_unused_result [-Wunused-result] gets(buff); ^ /tmp/cc1kM6Fx.o: In function `main': user.cpp:(.text.startup+0x9d): warning: the `gets' function is dangerous and should not be used.