#include <bits/stdc++.h>

#define FOR(i,a,b) for(int i= (a); i<((int)b); ++i)
#define RFOR(i,a) for(int i=(a); i >= 0; --i)
#define FOE(i,a) for(auto i : a)
#define ALL(c) (c).begin(), (c).end()
#define RALL(c) (c).rbegin(), (c).rend()
#define DUMP(x)  cerr << #x << " = " << (x) << endl;
#define SUM(x) std::accumulate(ALL(x), 0LL)
#define MIN(v) *std::min_element(v.begin(), v.end())
#define MAX(v) *std::max_element(v.begin(), v.end())
#define EXIST(v,x) (std::find(v.begin(), v.end(), x) != v.end())
#define BIT(n) (1LL<<(n))
#define UNIQUE(v) v.erase(unique(v.begin(), v.end()), v.end());

typedef long long LL;
template<typename T> using V = std::vector<T>;
template<typename T> using VV = std::vector<std::vector<T>>;
template<typename T> using VVV = std::vector<std::vector<std::vector<T>>>;

template<class T> inline T ceil(T a, T b) { return (a + b - 1) / b; }
template<class T> inline void print(T x) { std::cout << x << std::endl; }
template<class T> inline void print_vec(const std::vector<T> &v) { for (int i = 0; i < v.size(); ++i) {  if (i != 0) {std::cout << " ";} std::cout << v[i];} std::cout << "\n"; }
template<class T> inline bool inside(T y, T x, T H, T W) {return 0 <= y and y < H and 0 <= x and x < W; }
template<class T> inline double euclidean_distance(T y1, T x1, T y2, T x2) { return sqrt((x1 - x2) * (x1 - x2) + (y1 - y2) * (y1 - y2)); }
template<class T> inline double manhattan_distance(T y1, T x1, T y2, T x2) { return abs(x1 - x2) + abs(y1 - y2); }

const int INF = 1L << 30;
const double EPS = 1e-9;
const std::string YES = "YES", Yes = "Yes", NO = "NO", No = "No";
const std::vector<int> dy4 = { 0, 1, 0, -1 }, dx4 = { 1, 0, -1, 0 };    // 4近傍（右, 下, 左, 上）
const std::vector<int> dy8 = { 0, -1, 0, 1, 1, -1, -1, 1 }, dx8 = { 1, 0, -1, 0, 1, 1, -1, -1 };

using namespace std;

class FenwickTree {
public:
    const unsigned long n;
    std::vector<long long> v;

    FenwickTree(unsigned long n) : n(n) {
        this->v.assign(n + 1, 0);
    }

    // sum(v[0, i))
    long long sum(int i) {
        assert(0 <= i && i <= this->n);

        long long s = 0;
        i -= 1;
        while (i >= 0) {
            s += this->v[i];
            i = (i & (i + 1)) - 1;
        }
        return s;
    }

    // sum(v[left, right))
    long long sum(int left, int right) {
        assert(left <= right);
        return this->sum(right) - this->sum(left);
    }

    // v[i] += x(0-origin)
    void add(int i, long long x) {
        assert(i < this->n);

        while (i < this->n) {
            this->v.at(i) += x;
            i |= i + 1;
        }
    }
};


long long inversion(const vector<long long> &v) {
    FenwickTree ft(2 * 100000 + 10);

    long long ans = 0;
    for (int i = 0; i < v.size(); ++i) {
        ans += i - ft.sum(v[i]);
        ft.add(v[i], 1);
    }
    return ans;
}

LL calc(string from, string to) {
    int N = from.size();

    map<char, vector<int>> m;
    FOR(i, 0, N) {
        m[to[i]].emplace_back(i);
    }

    map<char, int> pos;
    vector<long long> t(N, -1);
    FOR(i, 0, N) {
        char c = from[i];
        int p = pos[c]++;
        t[i] = m[c][p];
    }

    return inversion(t);
}

LL solve(string s) {
    map<char, int> count1, count2;
    FOE(c, s) {
        count1[c]++;
    }

    char mi;
    int num_o = 0;
    FOE(p, count1) {
        if (p.second % 2 == 1) {
            mi = p.first;
            num_o++;
        }
    }

    if (num_o >= 2) {
        return -1;
    }

    string t;
    FOE(c, s) {
        count2[c]++;
        if (count2[c] * 2 <= count1[c]) {
            t += c;
        }
    }

    string ans(t);
    reverse(ALL(t));
    if (num_o == 1) {
        ans += mi;
    }
    ans += t;

    return calc(s, ans);
}


int main() {
    cin.tie(0);
    ios::sync_with_stdio(false);

    string s;
    cin >> s;
    print(solve(s));

    return 0;
}

Measured memory_bytes: 5776