text: #include <stdio.h>
  
  int main()
  {
      int n = 0;
      while (1)
      {
          printf("enter number (-1 to quit):");
          fflush(stdout);
          scanf("%d", &n);
          printf("you entered:%d\n", n);
  
          if (n == -1)
          {
              break;
          }
      }
      return 0;
  }
  