#include <bits/stdc++.h>
using namespace std;
constexpr int MOD = 1000000007;
using Long = long long;
template <typename T>
using V = vector<T>;
template <typename T>
using Vv = V<V<T>>;
using Vb = V<bool>;
using Vvb = V<Vb>;
using Vi = V<int>;
using Vvi = V<Vi>;
using Vl = V<Long>;
using Vvl = V<Vl>;
using Vd = V<double>;
using Vvd = V<Vd>;
using Vs = V<string>;
template <typename T>
T read() {
  T res;
  cin >> res;
  return res;
}
template <typename T>
V<T> readV(int n) {
  V<T> res((size_t)n);
  for (int i = 0; i < n; ++i) {
    res[i] = read<T>();
  }
  return res;
}
template <typename T>
Vv<T> readVv(int n, int m) {
  Vv<T> res((size_t)n, V<T>((size_t)m));
  for (int i = 0; i < n; ++i) {
    res[i] = readV<T>(m);
  }
  return res;
}
void solve() {
  int n;
  cin >> n;
  string s;
  cin >> s;
  vector<array<int, 3>> dp(n + 1);
  char colors[] = {'C', 'Y', 'M'};
  dp[n][0] = 1;
  dp[n][1] = 1;
  dp[n][2] = 1;
  for (int i = n - 1; i >= 0; --i) {
    for (int c = 0; c < 3; ++c) {
      int& val = dp[i][c];
      for (int nc = 0; nc < 3; ++nc) {
        if (c != nc && (colors[nc] == s[i] || s[i] == '?')) {
          val += dp[i + 1][nc];
        }
      }
      val = min(2, val);
    }
  }
  int ans = 0;
  if (s[0] == '?') {
    ans = dp[1][0] + dp[1][1] + dp[1][2];
  } else {
    ans = dp[1][find(colors, colors + 3, s[0]) - colors];
  }
  cout << (ans > 1 ? "Yes" : "No");
}
int main() {
  ios::sync_with_stdio(false);
  cin.tie(nullptr);
  cout.tie(nullptr);
  cout.precision(10);
  cout << fixed;
  solve();
  return 0;
}
