Compilare: user.cpp: In function ‘int main()’: user.cpp:67:34: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen ("robot2.in", "r", stdin); ^ user.cpp:68:36: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen ("robot2.out", "w", stdout); ^ user.cpp:70:19: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf ("%d\n", &N); ^ user.cpp:73:19: warning: ignoring return value of ‘char* gets(char*)’, declared with attribute warn_unused_result [-Wunused-result] gets (sir + 1); ^ user.cpp:77:42: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf ("%d %d %d %d", &X1, &Y1, &X2, &Y2); ^ /tmp/ccdtQR7U.o: In function `main': user.cpp:(.text.startup+0x7e): warning: the `gets' function is dangerous and should not be used.