#include<iostream>
#include<cstring>
using namespace std;
const int N=1010;
int n;
char s[N];
int f[N][N];
int main(){
cin>>s+1; n=strlen(s+1);
for(int len=1;len<=n;len++)
for(int i=1;i+len-1<=n&&i<=n-1;i++){
int j=i+len-1;
if(len==1) f[i][j]=1;
else{
f[i][j]=max(f[i+1][j],f[i][j-1]);
f[i][j]=max(f[i][j],f[i+1][j-1]+2*(s[i]==s[j]));
}
//cout<<f[i][j]<<endl;
}
cout<<n-f[1][n]<<endl;
return 0;
}