#include <bits/stdc++.h>
using namespace std;
int dx[8] = {0, 0, 1, -1, 1, 1, -1, -1};
int dy[8] = {1, -1, 0, 0, 1, -1, 1, -1};
template <typename T>
inline T BigMod(T A, T B) {
  T ret = 1;
  while (B) {
    if (B & 1) ret = (ret * A) % 1000000007;
    A = (A * A) % 1000000007;
    B = B >> 1;
  }
  return ret;
}
template <typename T>
inline T InvMod(T A, T M = 1000000007) {
  return BigMod(A, M - 2);
}
string tostring(long long int res) {
  string curstr = "";
  while (res != 0) {
    long long int temp = (res % 10);
    curstr += ((char)temp + '0');
    res /= 10;
  }
  reverse(curstr.begin(), curstr.end());
  return curstr;
}
long long int toint(string ss) {
  long long int inss = 0;
  for (int i = 0; i < ss.size(); i++) {
    inss = (inss * 10) + ((int)(ss[i] - '0'));
  }
  return inss;
}
int main() {
  string str;
  int n;
  scanf("%d", &n);
  cin >> str;
  int len = str.length(), cnt = 0;
  for (int i = 0; i < len; i++) {
    if (i == 0) {
      if (str[i] == '?') {
        cnt++;
      }
    }
    if (i == len - 1) {
      if (str[i] == '?') cnt++;
    } else {
      if (str[i - 1] == str[i + 1] && str[i] == '?') cnt++;
    }
  }
  for (int i = 0; i < len; i++) {
    if (str[i] == '?') {
      int j = i, cur = 0;
      while (j < len) {
        if (str[j] == '?')
          cur++, j++;
        else
          break;
      }
      if (cur >= 2)
        cnt++;
      else if (cur == 2) {
        if (j < len) {
          if (i != 0)
            if (str[i - 1] == str[j]) cnt++;
        }
      }
    }
  }
  for (int i = 0; i < len - 1; i++) {
    if (str[i] != '?') {
      if (str[i] == str[i + 1]) cnt = 0;
    }
  }
  if (cnt)
    printf("YES\n");
  else
    printf("NO\n");
  return 0;
}
