#pragma comment(linker, "/STACK:256000000")
#define _CRT_SECURE_NO_WARNINGS
#define _CRT_SECURE_NO_DEPRECATE
#include<iostream>
#include<cstdio>
#include<cstdlib>
#include<string>
#include<cstring>
#include<algorithm>
#include<cmath>
#include <set>
#include <queue>
#include <map>
#include <vector>
#include <unordered_map>
#include <assert.h>

using namespace std;

#define mp make_pair
#define pub push_back
#define con continue
#define forn(i, n) for (int i = 0; i < int(n); ++i)
#define fornr(i, n) for (int i = n - 1; i >= 0; --i)
#define forab(i, a, b) for (int i = (a); i <= int(b); ++i)
typedef long long ll;
typedef pair <int, int> pii;
typedef vector <int> vi;
typedef vector < pii > vii;
typedef vector < vector < int> > vvi;
typedef vector < vector < pair < int, int > > > vvii;

const int ZEROS = (int)(1E+6 * 5 + 100);
const int INF = (int)1E+9;
const long double EPS = 1E-13;

pii A[30];

void solve() {
    sort(A, A + 30);
    reverse(A, A + 30);

    int k = 0;
    int a1 = -1, a2 = -1, a3 = -1, a4 = -1;
    int x1 = 0, x2 = 0, x3 = 0, x4 = 0;
    forn(i, 30) {
        if (A[i].first > 0) {
            x1 = A[i].first;
            A[i].first--;
            a1 = A[i].second;
            forn(j, 30) {
                if (A[j].first > 0 && i != j) {
                    x2 = A[j].first;
                    A[j].first--;
                    a2 = A[j].second;
                    break;
                }
            }
            if (a2 != -1) {
                k++;
                break;
            }
        }
    }
    sort(A, A + 30);
    forn(i, 30) { //4
        if (A[i].first > 0 && A[i].second != a1 && A[i].second != a2) {
            x3 = A[i].first;
            A[i].first = 0;
            a3 = A[i].second;
            forn(j, 30) {
                if (A[j].first > 0 && i != j && A[j].second != a1 && A[j].second != a2) {
                    x4 = A[j].first;
                    A[j].first = 0;
                    a4 = A[j].second;
                    break;
                }
            }
            if (a4 != -1) {
                k++;
                break;
            }
            else
            {
                a3 = -1;
                A[i].first = x3;
            }
        }
    }
    bool u = false;
    forn(i, 30) {
        if (A[i].first > 0 && A[i].second != a1 && A[i].second != a2
            && A[i].second != a3 && A[i].second != a4) {
            u = true;
            break;
        }
    }
    if (k == 0 || (a1 != -1 && a2 != -1 && a3 != -1 && a4 != -1 && u)) {
        cout << "No";
        return;
    }
    if (k < 2) {
        A[a3].first = x3; A[a4].first = x4;
        a3 = -1; a4 = -1;
        k = 1;
        forn(i, 30) { //3
            if (A[i].first > 0 && A[i].second != a1 && A[i].second != a2) {
                x3 = A[i].first;
                A[i].first = 0;
                a3 = A[i].second;
                forn(j, 30) {
                    if (A[j].first > 0 && i != j) {
                        x4 = A[j].first;
                        A[j].first = 0;
                        a4 = A[j].second;
                        break;
                    }
                }
                if (a4 != -1) {
                    k++;
                    break;
                }
                else
                {
                    a3 = -1;
                    A[i].first = x3;
                }
            }
        }
        u = false;
        forn(i, 30) {
            if (A[i].first > 0 && A[i].second != a1 && A[i].second != a2
                && A[i].second != a3 && A[i].second != a4) {
                u = true;
                break;
            }
        }
        if (u || k < 2) {
            A[a3].first = x3; A[a4].first = x4;
            a3 = -1; a4 = -1;
            k = 1;
            forn(i, 30) { //2
                if (A[i].first > 0) {
                    x3 = A[i].first;
                    A[i].first = 0;
                    a3 = A[i].second;
                    forn(j, 30) {
                        if (A[j].first > 0 && i != j) {
                            x4 = A[j].first;
                            A[j].first = 0;
                            a4 = A[j].second;
                            break;
                        }
                    }
                    if (a4 != -1) {
                        k++;
                        break;
                    }
                    else
                    {
                        a3 = -1;
                        A[i].first = x3;
                    }
                }
            }
            u = false;
            forn(i, 30) {
                if (A[i].first > 0 && A[i].second != a1 && A[i].second != a2
                    && A[i].second != a3 && A[i].second != a4) {
                    u = true;
                    break;
                }
            }
            if (u || k < 2) {
                cout << "No";
                return;
            }
        }
    }
    cout << "Yes";
}

int main() {
#ifdef  _DEBUG
    freopen("input.txt", "r", stdin); freopen("output.txt", "w", stdout);
#endif
    ios_base::sync_with_stdio(0);
    cin.tie(0);

    string s;
    cin >> s;
    set <char> S;
    forn(i, (int)s.size()) {
        A[s[i] - 'a'].first++;
        A[s[i] - 'a'].second = s[i] - 'a';
    }
    solve();
}