#include<iomanip>
#include<limits>
#include<thread>
#include<utility>
#include<iostream>
#include<string>
#include<algorithm>
#include<set>
#include<map>
#include<vector>
#include<stack>
#include<queue>
#include<cmath>
#include<numeric>
#include<cassert>
#include<random>
#include<chrono>
#include<unordered_set>
#include<unordered_map>
#include<fstream>
#include<list>
#include<functional>
#include<bitset>
#include<complex>
#include<tuple>
using namespace std;
typedef unsigned long long int ull;
typedef long long int ll;
typedef pair<ll,ll> pll;
typedef long double D;
typedef complex<D> P;
#define F first
#define S second
const ll E=1e18+7;
const ll MOD=1000000007;

template<typename T,typename U>istream & operator >> (istream &i,pair<T,U> &A){i>>A.F>>A.S; return i;}
template<typename T>istream & operator >> (istream &i,vector<T> &A){for(auto &I:A){i>>I;} return i;}
template<typename T,typename U>ostream & operator << (ostream &o,const pair<T,U> &A){o<<A.F<<" "<<A.S; return o;}
template<typename T>ostream & operator << (ostream &o,const vector<T> &A){ll i=A.size(); for(auto &I:A){o<<I<<(--i?" ":"");} return o;}
template<typename T>vector<T> & cset(vector<T> &A,T e=T()){for(auto &I:A){I=e;} return A;}



using Int = long long;
//BEGIN CUT HERE
template <typename T,typename E>
struct SegmentTree{
    using F = function<T(T,T)>;
    using G = function<T(T,E)>;
    using H = function<E(E,E)>;
    int n,height;
    F f;
    G g;
    H h;
    T ti;
    E ei;
    vector<T> dat;
    vector<E> laz;
    SegmentTree(F f,G g,H h,T ti,E ei):
    f(f),g(g),h(h),ti(ti),ei(ei){}
    
    void init(int n_){
        n=1;height=0;
        while(n<n_) n<<=1,height++;
        dat.assign(2*n,ti);
        laz.assign(2*n,ei);
    }
    void build(const vector<T> &v){
        int n_=v.size();
        init(n_);
        for(int i=0;i<n_;i++) dat[n+i]=v[i];
        for(int i=n-1;i;i--)
            dat[i]=f(dat[(i<<1)|0],dat[(i<<1)|1]);
    }
    inline T reflect(int k){
        return laz[k]==ei?dat[k]:g(dat[k],laz[k]);
    }
    inline void eval(int k){
        if(laz[k]==ei) return;
        laz[(k<<1)|0]=h(laz[(k<<1)|0],laz[k]);
        laz[(k<<1)|1]=h(laz[(k<<1)|1],laz[k]);
        dat[k]=reflect(k);
        laz[k]=ei;
    }
    inline void thrust(int k){
        for(int i=height;i;i--) eval(k>>i);
    }
    inline void recalc(int k){
        while(k>>=1)
            dat[k]=f(reflect((k<<1)|0),reflect((k<<1)|1));
    }
    void update(int a,int b,E x){
        thrust(a+=n);
        thrust(b+=n-1);
        for(int l=a,r=b+1;l<r;l>>=1,r>>=1){
            if(l&1) laz[l]=h(laz[l],x),l++;
            if(r&1) --r,laz[r]=h(laz[r],x);
        }
        recalc(a);
        recalc(b);
    }
    void set_val(int a,T x){
        thrust(a+=n);
        dat[a]=x;laz[a]=ei;
        recalc(a);
    }
    T query(int a,int b){
        thrust(a+=n);
        thrust(b+=n-1);
        T vl=ti,vr=ti;
        for(int l=a,r=b+1;l<r;l>>=1,r>>=1) {
            if(l&1) vl=f(vl,reflect(l++));
            if(r&1) vr=f(reflect(--r),vr);
        }
        return f(vl,vr);
    }
    
    template<typename C>
    int find(int st,C &check,T &acc,int k,int l,int r){
        if(l+1==r){
            acc=f(acc,reflect(k));
            return check(acc)?k-n:-1;
        }
        eval(k);
        int m=(l+r)>>1;
        if(m<=st) return find(st,check,acc,(k<<1)|1,m,r);
        if(st<=l&&!check(f(acc,dat[k]))){
            acc=f(acc,dat[k]);
            return -1;
        }
        int vl=find(st,check,acc,(k<<1)|0,l,m);
        if(~vl) return vl;
        return find(st,check,acc,(k<<1)|1,m,r);
    }
    template<typename C>
    int find(int st,C &check){
        T acc=ti;
        return find(st,check,acc,1,0,n);
    }
};
//END CUT HERE



int main(){
    string s;
    cin>>s;
    vector<int> cnt1(26,0),cnt2(26,0),cnt3(26,0);
    for(auto &I:s){I-='a'; cnt1[I]++;}
    int odd=0;
    for(auto &I:cnt1){odd+=I&1;}
    if(odd>1){cout<<-1<<endl; return 0;}
    string A,B;
    map<pair<char,int>,int> M;
    ll ans=0;
    int dif=0;
    for(auto &I:s){
        cnt2[I]++;
        if(cnt1[I]&1 && cnt2[I]==(cnt1[I]+1)/2){ans+=B.size(); dif++; continue;}
        if(cnt2[I]*2<=cnt1[I]){M[pair<char,int>(I,cnt2[I])]=(int)A.size(); A.push_back(I); ans+=dif;}
        else{B.push_back(I); dif++;}
    }
    reverse(B.begin(),B.end());
    
    using P = pair<Int, Int>;
    auto f=[](P a,P b){return P(a.first+b.first,a.second+b.second);};
    auto g=[](P a,Int b){return P(a.first+b*a.second,a.second);};
    auto h=[](Int a,Int b){return a+b;};
    
    SegmentTree<P,Int> T(f,g,h,P(0,0),0);
    T.build(vector<P>(A.size(),P(1,1)));
    
    for(auto &I:B){
        cnt3[I]++;
        int idx=M[pair<char,int>(I,cnt3[I])];
        ans+=T.query(0,idx).F;
        T.update(idx,idx+1,-1);
    }
    cout<<ans<<endl;
    
    
    
    return 0;
}


Measured memory_bytes: 14724