C/C++ :: Do While Loop That Terminates Program When 99999 Is Entered?

I am trying to do a while loop that terminates the program when 99999 is entered but otherwise allows infinite integers to be entered. My problem is that when a negative number is entered it crashes and also when I enter a number it displays it twice.

#include <stdio.h>
#include <stdlib.h>
main() {
int number;
printf("Input an integer.
"); do {
scanf("%d",&number); /* read a single integer value in */
printf("%d
",number);
} while (number != 99999);
}