#include<bits/stdc++.h>

#define input freopen("input.txt", "r", stdin)
#define output freopen("output.txt", "w", stdout)

#define sc(a) scanf("%lld",&a)
#define pr(a) printf("%lld\n",a)

#define ll long long
#define vll vector<ll>
#define pb push_back

#define srt(a) sort(a.begin(),a.end())
#define rev(a) reverse(a.begin(),a.end())

#define inf 0x3f3f3f3f3f3f3f3fLL
#define mxn 1000005
#define mod 1000000007
#define pi acos(-1)

#define yes printf("YES\n")
#define no printf("NO\n")

#define r0 return 0

using namespace std;

string mirror="AHIMOTUVWXY";
string letter= "ABCDEFGHIJKLMNOPQRSTUVWXYZ";

int main()
{
    ll n,m,i,j,k,x,y,t;

    string s;

    cin>>s;

    ll f=0;

    n=s.size();

    for(i=0;i<n;i+=2){

        if(s[i]>='a' && s[i]<='z')continue;

        f=1;
    }

    for(i=1;i<n;i+=2){

        if(s[i]>='A' && s[i]<='Z')continue;

        f=1;
    }

    if(f)cout<<"No"<<endl;
    else cout<<"Yes"<<endl;
}

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

int main()
{
  string s, ans = "Yes";
  cin >> s;
  for (int i = 0; i < s.size(); i++)
  {
    if (i % 2 == 0)
    {
      if (s.at(i) <= 'Z')
        ans = "No";
    }
    else
    {
      if (s.at(i) > 'Z')
        ans = "No";
    }
  }
  cout << ans << endl;
}