a.cpp

#include <bits/stdc++.h>

using namespace std;

int main() {
    //freopen("input.txt", "rt", stdin);
    int ignored; cin >> ignored;
    string s; cin >> s;

    for (int i = 1; i < (int)s.size(); ++i) {
        if (s[i] == '?') continue;
        if (s[i] == s[i-1]) {
            cout << "No";
            return 0;
        }
    }

    for (int i = 1; i < (int)s.size(); ++i) {
        if (s[i] == '?' && s[i] == s[i-1]) {
            cout << "Yes";
            return 0;
        }
    }


    if (s.front() == '?' || s.back() == '?') {
        cout << "Yes";
        return 0;
    }

    for (int i = 1; i < (int)s.size()-1; ++i) {
        if (s[i] == '?' && s[i-1] == s[i+1]) {
            cout << "Yes"; return 0;
        }
    }

    cout << "No";

    return 0;
}