https://www.e-olymp.com/az/problems/19

#include <iostream>
/*
    Author: Kanan Asgarli
    https://www.e-olymp.com/az/problems/19
*/
using namespace std;
string num;
int ans, l;
int main() {
    cin>>num;
    l = num.length();
    for(int i = 0; i < l/2; i++){
        if(num[i] == num[l-1-i])
            ans++;
    }
    if(l%2 == 1)
        ans++;
    cout<<ans<<endl;
    return 0;
}