enter the string: 
1 15 ffffffd3 ffffffc7 fffffff4 ffffffe9 7a 23 42 ffffff81 ffffff9b ffffffe9 fffffff0 21 ffffff93 7 ffffffc7 ffffffe1 2b ffffffbf ffffffd4 71 ffffffee 6d 14 51 48 ffffffa1 4c 51 fffffff5 fffffff9 ffffffdc ffffffa9 4b ffffff87 72 ffffffa9 15 ffffff93 11 11 11 11 ffffffa1 ffffff81 ffffffdf 21 35 ffffff89 11 11 21 9 4f 61 ffffff95 39 11 11 ffffffd1 ffffff91 fffffff9 ffffffbd