import java.util.*;
import java.lang.*;
import java.io.*;
/* Name of the class has to be "Main" only if the class is public. */
class Codechef
{
{
// your code goes here
while(true) {
if(s.length()==1&&s.charAt(0)=='0') break;
int num=codeShef(s);
if(num
==-1) System.
out.
println("Impossible"); }
}
public static int codeShef
(String s
) { char[] ary=s.toCharArray();
boolean valid=true;
int res=0;
int i=0, j=ary.length-1;
while(i<j) {
//System.out.println(i);
//System.out.println(j);
if(ary[i]==ary[j]) {
i++;
j--;
continue;
}
boolean found=false;
int si=i+1;
int ej=j-1;
while(si<j&&ej>i) {
//System.out.println(si);
if(ary[si]==ary[j]) {
found=true;
while(si>i) {
res++;
ary[si]=ary[si-1];
si--;
}
ary[i]=ary[j];
break;
}
if(ary[ej]==ary[i]) {
while(ej<j) {
res++;
ary[ej]=ary[ej+1];
ej++;
}
ary[j]=ary[i];
found=true;
break;
}
si++;
ej--;
}
//System.out.println("eeee");
if(!found) return -1;
i++;
j--;
}
//System.out.println(new String(ary));
return res;
}
}
aW1wb3J0IGphdmEudXRpbC4qOwppbXBvcnQgamF2YS5sYW5nLio7CmltcG9ydCBqYXZhLmlvLio7CgovKiBOYW1lIG9mIHRoZSBjbGFzcyBoYXMgdG8gYmUgIk1haW4iIG9ubHkgaWYgdGhlIGNsYXNzIGlzIHB1YmxpYy4gKi8KY2xhc3MgQ29kZWNoZWYKewoJcHVibGljIHN0YXRpYyB2b2lkIG1haW4gKFN0cmluZ1tdIGFyZ3MpIHRocm93cyBqYXZhLmxhbmcuRXhjZXB0aW9uCgl7CgkJLy8geW91ciBjb2RlIGdvZXMgaGVyZQoJICAgIEJ1ZmZlcmVkUmVhZGVyIGJyID0gbmV3IEJ1ZmZlcmVkUmVhZGVyKG5ldyBJbnB1dFN0cmVhbVJlYWRlcihTeXN0ZW0uaW4pKTsKCQlTdHJpbmdCdWZmZXIgc2IgPSBuZXcgU3RyaW5nQnVmZmVyKCk7CgkJd2hpbGUodHJ1ZSkgewoJCQlTdHJpbmcgcyA9YnIucmVhZExpbmUoKTsKCQkJaWYocy5sZW5ndGgoKT09MSYmcy5jaGFyQXQoMCk9PScwJykgYnJlYWs7CgkJCWludCBudW09Y29kZVNoZWYocyk7CgkJCWlmKG51bT09LTEpIFN5c3RlbS5vdXQucHJpbnRsbigiSW1wb3NzaWJsZSIpOwoJCQllbHNlIFN5c3RlbS5vdXQucHJpbnRsbihudW0pOwoJCX0KCX0KCQlwdWJsaWMgc3RhdGljIGludCBjb2RlU2hlZihTdHJpbmcgcykgewoJCWNoYXJbXSBhcnk9cy50b0NoYXJBcnJheSgpOwoJCWJvb2xlYW4gdmFsaWQ9dHJ1ZTsKCQlpbnQgcmVzPTA7CgkJaW50IGk9MCwgaj1hcnkubGVuZ3RoLTE7CgkJd2hpbGUoaTxqKSB7CgkJCS8vU3lzdGVtLm91dC5wcmludGxuKGkpOwoJCQkvL1N5c3RlbS5vdXQucHJpbnRsbihqKTsKCQkJaWYoYXJ5W2ldPT1hcnlbal0pIHsKCQkJCWkrKzsKCQkJCWotLTsKCQkJCWNvbnRpbnVlOwoJCQl9CgkJCWJvb2xlYW4gZm91bmQ9ZmFsc2U7CgkJCWludCBzaT1pKzE7CgkJCWludCBlaj1qLTE7CgkJCXdoaWxlKHNpPGomJmVqPmkpIHsKCQkJCS8vU3lzdGVtLm91dC5wcmludGxuKHNpKTsKCQkJCWlmKGFyeVtzaV09PWFyeVtqXSkgewoJCQkJCWZvdW5kPXRydWU7CgkJCQkJd2hpbGUoc2k+aSkgewoJCQkJCQlyZXMrKzsKCQkJCQkJYXJ5W3NpXT1hcnlbc2ktMV07CgkJCQkJCXNpLS07CgkJCQkJfQoJCQkJCWFyeVtpXT1hcnlbal07CgkJCQkJYnJlYWs7CgkJCQl9CgkJCQlpZihhcnlbZWpdPT1hcnlbaV0pIHsKCQkJCQl3aGlsZShlajxqKSB7CgkJCQkJCXJlcysrOwoJCQkJCQlhcnlbZWpdPWFyeVtlaisxXTsKCQkJCQkJZWorKzsKCQkJCQl9CgkJCQkJYXJ5W2pdPWFyeVtpXTsKCQkJCQlmb3VuZD10cnVlOwoJCQkJCWJyZWFrOwoJCQkJfQoJCQkJc2krKzsKCQkJCWVqLS07CgkJCX0KCQkJLy9TeXN0ZW0ub3V0LnByaW50bG4oImVlZWUiKTsKCQkJaWYoIWZvdW5kKSByZXR1cm4gLTE7CgkJCWkrKzsKCQkJai0tOwoJCQkKCQl9CgkJLy9TeXN0ZW0ub3V0LnByaW50bG4obmV3IFN0cmluZyhhcnkpKTsKCQlyZXR1cm4gcmVzOwoJCQoJfQoJCn0=