#include <bits/stdc++.h>
using namespace std;
char s[105];
int main() {
  int n;
  cin >> n;
  cin >> s;
  int flag = 0;
  for (int i = 1; i < n; i++) {
    if (s[i] != '?' && s[i] == s[i - 1]) {
      flag = 1;
      break;
    }
  }
  if (flag)
    cout << "No" << endl;
  else {
    if (s[0] == '?' || s[n - 1] == '?')
      flag = 1;
    else {
      for (int i = 1; i < n - 1; i++) {
        if (s[i] == '?' && s[i - 1] == '?' ||
            s[i] == '?' && s[i + 1] == s[i - 1])
          flag = 1;
      }
    }
    if (flag)
      cout << "Yes" << endl;
    else
      cout << "No" << endl;
  }
  return 0;
}
