#include <bits/stdc++.h>
using namespace std;
string c = "CMY";
int n;
string s, x;
set<string> st;
bool solve(int i) {
  if (i == n) {
    st.insert(s);
    return true;
  }
  if (s[i] == '?') {
    bool ans = false;
    int cnt = 0;
    for (int j = 0; j < 3; j++) {
      if (i == 0) {
        s[i] = c[j];
        ans = solve(i + 1);
      } else {
        if (c[j] != s[i - 1]) {
          s[i] = c[j];
          bool t = solve(i + 1);
          ans = ans or t;
          cnt += (t == true);
        }
      }
    }
    if (cnt > 1) {
      cout << "Yes\n";
      exit(0);
    }
    s[i] = '?';
    return ans;
  } else {
    if (i == 0) {
      return solve(i + 1);
    } else {
      if (s[i] == s[i - 1]) {
        if (x[i] != '?' and x[i - 1] != '?') {
          cout << "No\n";
          exit(0);
        }
        return false;
      } else {
        return solve(i + 1);
      }
    }
  }
}
int main() {
  cin >> n >> s;
  x = s;
  bool ans = solve(0);
  if (ans and st.size() > 1) {
    cout << "Yes\n";
  } else {
    cout << "No\n";
  }
  return 0;
}
