Problem:
Score : 700 points

Problem Statement

We have a string s consisting of lowercase English letters.
Snuke is partitioning s into some number of non-empty substrings.
Let the subtrings obtained be s_1, s_2, ..., s_N from left to right. (Here, s = s_1 + s_2 + ... + s_N holds.)
Snuke wants to satisfy the following condition:

For each i (1 \leq i \leq N), it is possible to permute the characters in s_i and obtain a palindrome.

Find the minimum possible value of N when the partition satisfies the condition.

Constraints

1 \leq |s| \leq 2 \times 10^5

s consists of lowercase English letters.

Input

Input is given from Standard Input in the following format:

s

Output

Print the minimum possible value of N when the partition satisfies the condition.

Sample Input 1

aabxyyzz

Sample Output 1

2

The solution is to partition s as aabxyyzz = aab + xyyzz.
Here, aab can be permuted to form a palindrome aba, and xyyzz can be permuted to form a palindrome zyxyz.

Sample Input 2

byebye

Sample Output 2

1

byebye can be permuted to form a palindrome byeeyb.

Sample Input 3

abcdefghijklmnopqrstuvwxyz

Sample Output 3

26

Sample Input 4

abcabcxabcx

Sample Output 4

3

The solution is to partition s as abcabcxabcx = a + b + cabcxabcx.

Solution in C++14 (GCC 5.4.1) (judge verdict: Wrong Answer)

#include <bits/stdc++.h>
using namespace std;
#define DEBUG_MODE
#define endl '\n'
#ifdef DEBUG_MODE
#define DEBUG(...) debug_func_mult(split_names(#__VA_ARGS__), __VA_ARGS__)
#define DEBUG_ENDL endl << flush
#define DEBUG_SEPARATOR_LINE cout<<"=================\n"
#else
#define DEBUG(...) 0
#define DEBUG_ENDL 0
#define DEBUG_SEPARATOR_LINE 0
#endif
#define ALL(V) (V).begin(), (V).end()
#define ALLR(V) (V).rbegin(), (V).rend()
#define DEBUG_ENDL_S(S) ((S).size() ? "\n" : "") << flush;

template <typename T> using V = vector<T>;
template <typename T> using VV = V<V<T>>;
template <typename T, typename U> using P = pair<T, U>;
using ll = int64_t;
using PLL = P<ll, ll>;

template <typename T> const T& var_min(const T &t) { return t; }
template <typename T> const T& var_max(const T &t) { return t; }
template <typename Head, typename... Tail> const Head& var_min(const Head &head, const Tail&... tail) { return min(head, var_min(tail...)); }
template <typename Head, typename... Tail> const Head& var_max(const Head &head, const Tail&... tail) { return max(head, var_max(tail...)); }
template <typename T, typename... Tail> void chmin(T &t, const Tail&... tail) { t = var_min(t, tail...); }
template <typename T, typename... Tail> void chmax(T &t, const Tail&... tail) { t = var_max(t, tail...); }

string to_string(const string &s) { return s; }
template <typename T> string to_string(const V<T> &v);

template <typename T, typename U>
string to_string(const P<T, U> &p) {
    string ret = "(";
    ret += to_string(p.first);
    ret += ", ";
    ret += to_string(p.second);
    ret += ")";
    return move(ret);
}

template <typename T>
string to_string(const V<T> &v) {
    string ret = "{";
    for(const T &t : v) {
        ret += to_string(t);
        ret += ", ";
    }
    ret += "}";
    return move(ret);
}

template <typename T>
void debug_func(const T &t, const string &s = "") {
    if(s.size()) cout << s << " = ";
    cout << to_string(t) << DEBUG_ENDL_S(s);
}

template <typename T>
void debug_func_mult(int idx, const V<string> &names, const T &t) {
    debug_func(t, names[idx]);
}

template <typename T>
void debug_func_mult(const V<string> &names, const T &t) {
    debug_func(t, names[0]);
}

template <typename Head, typename... Tail>
void debug_func_mult(int idx, const V<string> &names, const Head &head, const Tail&... args) {
    debug_func(head, names[idx]);
    debug_func_mult(idx + 1, names, args...);
}

template <typename Head, typename... Tail>
void debug_func_mult(const V<string> &names, const Head &head, const Tail&... args) {
    debug_func(head, names[0]);
    debug_func_mult(1, names, args...);
}

V<string> split_names(string &&s) {
    replace(ALL(s), ' ', ',');
    V<string> ret;
    istringstream ss(s);
    string t;
    while(getline(ss, t, ',')) if(t.size()) ret.push_back(move(t));
    return move(ret);
}

void init_io() {
    cin.tie(0);
    ios_base::sync_with_stdio(false);
    cout << fixed << setprecision(30);
}

const ll INF = 5e15;
map<ll, V<ll>> idxv;
//VV<ll> idxv(1ll << 26);
V<ll> oev;
V<ll> memo(2e5 + 10, INF);
string S;

ll calc(ll idx) {
    if(memo[idx] != INF) return memo[idx];
    if(idx > S.size()) return 0;
    ll bs = oev[idx];
    ll ret = calc(idx + 1) + 1;
    {
        ll tmp = idxv[bs].back();
        if(tmp > idx) chmin(ret, calc(tmp) + 1);
    }
    for(ll i = 0; i < 26; i++) {
        ll nidx = bs ^ (1ll << i);
        const auto &v = idxv[nidx];
        if(v.size() == 0) continue;
        ll right = v.back();
        if(right < idx) continue;
        chmin(ret, calc(right) + 1);
    }
    return memo[idx] = ret;
}

int main() {
    init_io();
    cin >> S;
    ll now = 0;
    oev.push_back(0);
    idxv[0].push_back(0);
    for(ll i = 0; i < S.size(); i++) {
        now ^= (1ll << (S[i] - 'a'));
        oev.push_back(now);
        idxv[now].push_back(i + 1);
        //idxv[now].push_back(i);
    }
    
    cout << calc(0) - 1 << endl;
    return 0;
}