#include <iostream>
#include <vector>
#include <string>
#include <algorithm>
#include <math.h>
#include <set>
using namespace std;
vector<char> pool = { 'C','M','Y' };
bool bad = true, overall_good = false;
bool check(string& vars)
{
    if (vars.length() == 2)
    {
        if (vars[0] == vars[1])
            return true;
    }
    else
    {
        for (int i = 1; i < vars.length() - 1; i++)
        {
            if (vars[i - 1] == vars[i] || vars[i] == vars[i + 1])
                return true;
        }
    }
    return false;
}
void generate(string& vars, vector<int>& map, int id)
{
    bool skip;
    for (int i = 0; i < 3; i++)
    {
        skip = false;
        if (overall_good)
            break;
        if (id > 0 && map[id - 1] == map[id] - 1 && pool[i] == vars[map[id-1]])
        {
            skip = true;
        }
        else
            vars[map[id]] = pool[i];
        if (id + 1 > map.size() - 1 && !skip)
        {
            bool new_bad = check(vars);
            if (!bad && !new_bad)
            {
                overall_good = true;
                break;
            }
            else if (!new_bad) bad = new_bad;
        }
        else if (!skip) generate(vars, map, id + 1);
    }
}
int main()
{
    int n;
    vector<int> var;
    string a;
    cin >> n;
    cin >> a;
    for (int i = 0; i < n; i++)
    {
        if (a[i] == '?')
            var.push_back(i);
    }
    if (var.size() > 0)
        generate(a, var, 0);
    else overall_good = !check(a);
    if (!overall_good)
        cout << "No";
    else cout << "Yes";
    return 0;
}