#include <bits/stdc++.h>
using namespace std;
const long long int N = 1e5;
int32_t main() {
  ios_base::sync_with_stdio(false);
  cin.tie(0);
  cout.tie(0);
  long long int tc = 1;
  for (long long int T = 1; T <= tc; T++) {
    long long int n;
    cin >> n;
    string s;
    cin >> s;
    long long int cnt = 0, flag = 0;
    for (long long int i = 0; i < n - 1; i++) {
      if (s[i] == s[i + 1] and s[i] != '?') {
        flag = 1;
        break;
      }
    }
    if (flag) {
      cout << "No\n";
      return 0;
    }
    if (s[0] == '?' or s[n - 1] == '?') {
      cout << "Yes\n";
      return 0;
    }
    long long int tot = 0, ok = 0;
    char start = '$', end = '$';
    for (long long int i = 0; i < n; i++) {
      if (s[i] != '?' and flag == 0) {
        start = s[i];
      } else if (s[i] == '?') {
        cnt++;
        flag = 1;
      } else {
        end = s[i];
        if (cnt == 1) {
          if (start == end) {
            ok = 1;
            break;
          }
        } else {
          ok = 1;
          break;
        }
        start = end;
        cnt = 0;
        flag = 0;
      }
    }
    if (ok)
      cout << "Yes\n";
    else
      cout << "No\n";
  }
  return 0;
}
