Compilare: user.cpp: In function ‘int main()’: user.cpp:26:30: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d%d", &N, &M); ^ user.cpp:27:70: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d%d%d%d\n", &start.x, &start.y, &finish.x, &finish.y); ^ user.cpp: In function ‘void Read()’: user.cpp:83:20: warning: ignoring return value of ‘char* gets(char*)’, declared with attribute warn_unused_result [-Wunused-result] gets(S + 2); ^ /tmp/cc0hF9FM.o: In function `Read()': user.cpp:(.text+0xf8): warning: the `gets' function is dangerous and should not be used.