#include <bits/stdc++.h>
using namespace std;

using VI = vector<int>;
using VVI = vector<VI>;
using PII = pair<int, int>;
using LL = long long;
using VL = vector<LL>;
using VVL = vector<VL>;
using PLL = pair<LL, LL>;
using VS = vector<string>;

#define ALL(a)  begin((a)),end((a))
#define RALL(a) (a).rbegin(), (a).rend()
#define PB push_back
#define EB emplace_back
#define MP make_pair
#define SZ(a) int((a).size())
#define SORT(c) sort(ALL((c)))
#define RSORT(c) sort(RALL((c)))
#define UNIQ(c) (c).erase(unique(ALL((c))), end((c)))

#define FOR(i,a,b) for(int i=(a);i<(b);++i)
#define REP(i,n)  FOR(i,0,n)

#define FF first
#define SS second

#define DUMP(x) cout<<#x<<":"<<(x)<<endl
template<class S, class T>
istream& operator>>(istream& is, pair<S,T>& p){
  return is >> p.FF >> p.SS;
}
template<class T>
istream& operator>>(istream& is, vector<T>& xs){
  for(auto& x: xs)
	is >> x;
  return is;
}
template<class S, class T>
ostream& operator<<(ostream& os, const pair<S,T>& p){
  return os << p.FF << " " << p.SS;
}
template<class T>
ostream& operator<<(ostream& os, const vector<T>& xs){
  for(unsigned int i=0;i<xs.size();++i)
	os << (i?" ":"") << xs[i];
  return os;
}
template<class T>
void maxi(T& x, T y){
  if(x < y) x = y;
}
template<class T>
void mini(T& x, T y){
  if(x > y) x = y;
}


const double EPS = 1e-10;
const double PI  = acos(-1.0);
const LL MOD = 1e9+7;

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

  string S;
  cin >> S;

  VI cnt1(26), cnt2(10);
  for(char c: S)
	if(isdigit(c))
	  cnt2[c-'0']++;
	else
	  cnt1[c-'a']++;

  int len = 0;
  while(count(ALL(cnt1), 0) < 26){
	int b = 0;
	for(;;++b) if(cnt1[b]) break;
	int e = b+1;
	for(;e<26;++e) if(!cnt1[e]) break;
	if(e-b >= 3){
	  FOR(i,b,e) --cnt1[i];
	  len += 3;
	}
	else{
	  --cnt1[b];
	  ++len;
	}
  }
  while(count(ALL(cnt2), 0) < 10){
	int b = 0;
	for(;;++b) if(cnt2[b]) break;
	int e = b+1;
	for(;e<10;++e) if(!cnt2[e]) break;
	if(e-b >= 3){
	  FOR(i,b,e) --cnt2[i];
	  len += 3;
	}
	else{
	  --cnt2[b];
	  ++len;
	}
  }

  cout << len << endl;

  return 0;
}

