#include <bits/stdc++.h>
#define speed ios_base::sync_with_stdio(0); cin.tie(0)
#define all(x) (x).begin(),(x).end()
#define F first
#define S second
//#pragma GCC optimize("O3,unroll-loops")
//#pragma GCC target("avx,avx2")
//#pragma GCC target("popcnt")
using namespace std;
typedef long long ll;
typedef unsigned long long ull;
typedef double db;
typedef long double ldb;
typedef pair<int,int> pii;
typedef pair<ll,ll> pll;
const ll MAX=1e5+10,P=1e9+7;
const ll INF=0x3f3f3f3f,oo=0x3f3f3f3f3f3f3f3f;
const ldb eps=1e-6;
const ldb PI=acos(-1.0);
const int dir[4][2]={{0,1},{0,-1},{1,0},{-1,0}};
template<typename T>
using vvector = vector<vector<T>>;
int pas[15][15][MAX],rpas[15][15][MAX];
vector<int> pos[20];
int g;
ldb calc(ldb x,int st,int can) {
ldb ans=0;
ll k=(x?pos[can][x-1]:0);
// cout<<x<<" "<<k<<" xk\n";
for (int i=0;i<g;i++) {
if (st&(1<<i)) {
ans+=pas[i][can][k]+rpas[i][can][k+1];
}
}
ldb n = pos[can].size();
return ans+x*(x-1)/4+(n-x)*(n-x-1)/4;
}
int main() {
speed;
string s;
cin>>s;
vector<int> d;
for (char c:s) d.push_back(c);
sort(all(d));
d.resize(unique(all(d))-d.begin());
int n=s.size();
for (int i=0;i<n;i++) {
pos[lower_bound(all(d),s[i])-d.begin()].push_back(i);
}
g=d.size();
// for (int i=0;i<g;i++) {
// for (int j:pos[i]) cout<<j<<" ";
// cout<<" pos\n";
// }
// cout<<"g "<<g<<"\n";
for (int i=0;i<g;i++) {
for (int j=0;j<g;j++) {
int iid=0,jid=0;
pas[i][j][0]=0;
ll cnt=0;
for (int k=0;k<n;k++) {
if (iid<pos[i].size() and pos[i][iid]==k) {
cnt++;
iid++;
}
if (jid<pos[j].size() and pos[j][jid]==k) {
if (k>0) pas[i][j][k]=pas[i][j][k-1]+cnt;
jid++;
} else pas[i][j][k]=pas[i][j][k-1];
// cout<<i<<" "<<j<<" "<<k<<" "<<iid<<" "<<jid<<" "<<cnt<<" "<<pas[i][j][k]<<" pas\n";
}
}
}
for (int i=0;i<g;i++) {
for (int j=0;j<g;j++) {
int iid=pos[i].size()-1,jid=pos[j].size()-1;
rpas[i][j][n]=0;
ll cnt=0;
for (int k=n-1;k>=0;k--) {
if (iid>=0 and pos[i][iid]==k) {
cnt++;
iid--;
}
if (jid>=0 and pos[j][jid]==k) {
rpas[i][j][k]=rpas[i][j][k+1]+cnt;
jid--;
} else rpas[i][j][k]=rpas[i][j][k+1];
}
}
}
ldb dp[1<<16];
for (int st=1;st<(1<<g);st++) dp[st]=oo;
dp[0]=0;
for (int st=0;st<(1<<g);st++) {
for (int i=0;i<g;i++) {
if (st&(1<<i)) continue;
int l=0,r=pos[i].size();
// cout<<l<<" "<<r<<" l r\n";
while (l+2<r) {
int mid1=(l+r)/2;
int mid2=mid1+1;
// cout<<st<<" "<<i<<" st can\n";
// cout<<mid1<<" "<<calc(mid1,st,i)<<" mid1\n";
// cout<<mid2<<" "<<calc(mid2,st,i)<<" mid2\n";
if (calc(mid1,st,i)<calc(mid2,st,i)) r=mid2;
else l=mid1;
}
for (int k=l;k<=r;k++) {
// cout<<k<<" "<<calc(k,st,i)<<" k calc\n";
dp[st|(1<<i)]=min(dp[st|(1<<i)],dp[st]+calc(k,st,i));
}
}
}
cout<<dp[(1<<g)-1]<<"\n";
return 0;
}
// HEHEHEHIHILOL
