#include <iostream>
#include <vector>
#include <string>
#include <cctype>
using namespace std;

int main() {
    string S;
    getline(cin, S);
    int n = S.size();
    
    for (int p : {0, 1}) {
        vector<bool> B(26, false);
        for (int i = 0; i < n; ++i) {
            if ((i + 1) % 2!= p && islower(S[i])) {
                B[S[i] - 'a'] = true;
            }
        }
        
        vector<int> non_blanks;
        for (int i = 0; i < n; ++i) {
            if ((i + 1) % 2 == p && islower(S[i]) &&!B[S[i] - 'a']) {
                non_blanks.push_back(i + 1);
            }
        }
        
        if (non_blanks.empty()) continue;
        
        int first = non_blanks[0];
        int last = non_blanks.back();
        int expected = (last - first) / 2 + 1;
        
        if (non_blanks.size()!= expected) continue;
        
        if (last > first) {
            cout << "Yes\n";
            return 0;
        } else {
            if (first + 1 <= n) {
                cout << "Yes\n";
                return 0;
            }
        }
    }
    
    cout << "NO\n";
    return 0;
}