#include <algorithm>
#include <bitset>
#include <complex>
#include <deque>
#include <iostream>
#include <istream>
#include <iterator>
#include <map>
#include <queue>
#include <set>
#include <stack>
#include <string>
#include <vector>
#include <tuple>
#include <iomanip>
#include <climits>
using namespace std;

typedef long long ll;
typedef unsigned long long ull;
//typedef pair<ll, ll> P;
#define rep(i, n) for(ll i = 0; i < (n); i++)
#define revrep(i, n) for(ll i = (n)-1; i >= 0; i--)
#define pb push_back
#define f first
#define s second
#define chmin(x, y) x = min(x, y);
#define chmax(x, y) x = max(x, y);

//const ll INFL = LLONG_MAX;//10^18 = 2^60
const ll INFL = 1LL<<60;
//const int INF = INT_MAX;
const ll INF = 1 << 30;//10^9
ll MOD = 1000000007;
//ll MOD = 998244353;

vector<ll> dy = {0, 1, 0, -1, 1, 1, -1, -1, 0};
vector<ll> dx = {1, 0, -1, 0, 1, -1, 1, -1, 0};

void pres(double A, ll x = 20){cout << fixed << setprecision(x) << A << endl;}
void BinarySay(ll x, ll y = 60){rep(i, y) cout << (x>>(y-1-i) & 1); cout << endl;}
ll cnt_bit(ll x){return __builtin_popcountll(x);}

ll pow_long(ll x, ll k){
  ll res = 1;
  while(k > 0){
    if(k % 2) res *= x;
    x *= x; k /= 2;
  }
  return res;
}

ll pow_mod(ll x, ll k){
  ll res = 1;
  while(k > 0){
    if(k % 2){
      res *= x; res %= MOD;
    }
    x *= x; x %= MOD;
    k /= 2;
  }
  return res;
}

ll inverse(ll x){return pow_mod(x, MOD - 2);};

ll gcd(ll a, ll b){
    if(b == 0) return a;
    return gcd(b, a % b);
}

ll lcm(ll x, ll y){
  ll res = x / gcd(x, y);
  res *= y;
  return res;
};

//コンビネーション
const int MAXcomb = 200010;
ll fac[MAXcomb], finv[MAXcomb], inv[MAXcomb];
//facはn!,finvは1/n!
//invは逆元
void COMinit(){
    fac[0] = fac[1] = 1;
    finv[0] = finv[1] = 1;
    inv[1] = 1;
    for(int i = 2; i < MAXcomb; i++){
        fac[i] = fac[i-1] * i % MOD;
        inv[i] = MOD - inv[MOD%i] * (MOD/i) % MOD;
        finv[i] = finv[i-1] * inv[i] % MOD;
    }
}
ll comb(int n, int k){
    if(n < k) return 0;
    if(n < 0 || k < 0) return 0;
    return fac[n] * finv[k] % MOD * finv[n-k] % MOD;
}

const int MAXkai = 200010;
ll kai_memo[MAXkai];
ll kai(ll N){
  if(kai_memo[N] != 0) return kai_memo[N];
  if(N <= 1) return 1;
  return kai_memo[N] = N * kai(N-1) % MOD;
}

ll tnt(ll l, ll r, vector<ll> &A){//[l, r)
  ll res = 0;
  ll mid = (l+r)/2;
  if(r - l == 1) return res;
  res += tnt(l, mid, A);
  res += tnt(mid, r, A);
  vector<ll> B;
  ll x = l, y = mid;
  while(x < mid || y < r){
    ll bs = B.size();
    if(x == mid){
      B.pb(A[y++]);
    }else if(y == r){
      res += bs - x + l;
      B.pb(A[x++]);
    }else{
      //A[x] <= A[y] でイコールを含める転倒数
      if(A[x] < A[y]){
        res += bs - x + l;
        B.pb(A[x++]);
      }else{
        B.pb(A[y++]);
      }
    }
  }
  for(ll i = l; i < r; i++) A[i] = B[i-l];
  return res;
}

vector<ll> E[26];
ll dist(string S, string T){
  ll N = T.size();
  rep(i, N){
    E[S[i] - 'a'].pb(i);
  }
  rep(i, 26) E[i].pb(INFL);
  vector<ll> now(26, 0);
  vector<ll> A(N);
  rep(i, N){
    ll c = T[i] - 'a';
    A[E[c][now[c]]] = i;
    now[T[i] - 'a']++;
  }
  ll res = tnt(0, N, A);

  return res;
}

void solve(){
  string S;
  cin >> S;
  if(S.size() == 1){
    cout << 0 << endl;
    return;
  }
  ll N = S.size();
  vector<ll> cnt(26, 0);
  rep(i, N) cnt[S[i] - 'a']++;
  ll odd = 0;
  rep(i, 26)if(cnt[i] % 2) odd++;
  if(odd >= 2){
    cout << -1 << endl;
    return;
  }
  vector<ll> to(N);
  vector<ll> now(26, 0);
  rep(i, N){
    ll c = S[i] - 'a';
    now[c]++;
    if(cnt[c] % 2){
      if(cnt[c] / 2 + 1 == now[c]) to[i] = 1;
      else if(cnt[c] / 2 + 1 < now[c]) to[i] = 2;
      else to[i] = 0;
    }else{
      if(cnt[c] / 2 < now[c]) to[i] = 2;
      else to[i] = 0;
    }
  }

  ll ans = 0;
  ll a = 0, b = 0, c = 0;
  rep(i, N){
    if(to[i] == 0){
      ans += b + c;
      a++;
    }else if(to[i] == 1){
      ans += c;
      b++;
    }else{
      c++;
    }
  }
  string T, U;
  rep(i, N){
    if(to[i] == 0) T += S[i];
    if(to[i] == 2) U += S[i];
  }
  reverse(T.begin(), T.end());
  ans += dist(T, U);
  cout << ans << endl;
}

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


Measured memory_bytes: 6028