#include <bits/stdc++.h>
using namespace std;
const long long mx = 105;
const long long maxn = 1000001;
const long long mod = 998244353;
vector<vector<int>> adj;
vector<int> res;
vector<int> ord;
vector<string> v;
void solve() {
  long long n, i, j, k;
  string s;
  cin >> n;
  cin >> s;
  int flag = 0, pos = 1;
  for (i = 1; i < (int)s.size(); i++) {
    if (s[i] == s[i - 1] && s[i] != '?') {
      pos = 0;
      break;
    }
  }
  for (i = 1; i < (int)s.size(); i++) {
    if (s[i] == s[i - 1] && s[i] == '?') {
      flag = 1;
      break;
    }
  }
  for (i = 1; i < (int)s.size() - 1; i++) {
    if (s[i] == '?' && s[i - 1] == s[i + 1]) {
      flag = 1;
      break;
    }
  }
  if (s[0] == '?' || s[n - 1] == '?') {
    flag = 1;
  }
  if (!pos) {
    cout << "No\n";
  } else {
    if (flag) {
      cout << "Yes\n";
    } else {
      cout << "No\n";
    }
  }
}
int main() {
  ios_base::sync_with_stdio(false);
  cin.tie(0);
  long long t = 1;
  while (t--) {
    solve();
  }
}
