#include <bits/stdc++.h>
using namespace std;

#define itloop(it,x) for(auto it=x.begin();it!=x.end();it++)
#define reloop(i,e,b) for(auto i=e;i>=b;i--)
#define loop(i,b,e) for(auto i=b;i<=e;i++)
#define ALL(x) x.begin(),x.end()
#define SZ(x) x.size()
#define PB push_back
#define MP make_pair
#define F first
#define S second
#define sf scanf
#define pf printf
typedef long long LL;
typedef vector<int> VI;
typedef vector<LL> VLL;
typedef pair<int,int> PI;
typedef pair<LL,LL> PL;

int n,un,x,y,z;
string c;

int main()
{
   cin >> n >> c;
   loop(i,0,c.length()-1) {
      if(c[i] == '?')
         un++;
   }
   if(un == 0 || un == 1)
      cout << "No";
   else {
      loop(i,0,c.length()-1) {
         if(c[i] == '?') {
            if(c[i-1] != 'C' && c[i+1] != 'C')
               c[i] = 'C',x++;
            if(c[i-1] != 'Y' && c[i+1] != 'Y')
               c[i] = 'Y',y++;
            if(c[i-1] != 'M' && c[i+1] != 'M')
               c[i] = 'M',z++;
         }
      }
      puts(min(x,min(y,z)) == 0 ? "Yes" : "No");
   }
}