include <bits/stdc++.h>

using namespace std;

define ll long long

define push_b push_back

define ss stringstream

define pqueue priority_queue

define ft first

define se second

const int mod = 1e9 + 7;
int dem[256];
int main(){
ios::sync_with_stdio(false);
cin.tie(0);
cout.tie(0);
string s; cin >> s;
for(int i = 0; i < s.size(); ++i){
for(int j = i - 1; j >= 0; --j){
if(s[i] == s[j]){
++dem[s[i]];
}
}
}
cout << *max_element(dem + 97, dem + 123);
}