#include <bits/stdc++.h>

using namespace std;

int main() {
  ios::sync_with_stdio(false);
  cin.tie(0);
  string s;
  cin>>s;
  bool ok=true;
  for ( int i=0; i<s.size(); i++ ) {
    if ( isupper(s[i]) ) {
      if ( i%2==0 ) ok=false;
    } else {
      if ( i%2 ) ok=false;
    }
  }
  if ( ok ) cout<<"Yes\n";
  else cout<<"No\n";
  return 0;
}
#include <bits/stdc++.h>
#define ios ios::sync_with_stdio(false), cin.tie(0);
#define et cout<<endl;
using namespace std;
typedef pair<int, int> PII;
typedef long long ll;
typedef unsigned long long ull;
inline int read()
{
    int x=0,f=1;char ch=getchar();
    while (!isdigit(ch)){if (ch=='-') f=-1;ch=getchar();}
    while (isdigit(ch)){x=x*10+ch-48;ch=getchar();}
    return x*f;
}
const int N = 2e5+5;
const int M = 2e5+5;
const int mod = 1e9+7;
int t, n, k;
int g[N];
char s[N];
void solve()
{
    cin >> s + 1;
    int len = strlen(s+1);
    bool even = true, odd = true;
    for(int i = 1; i <= len; i ++)
    {
        if(i & 1)
        {
            if(s[i] >= 'a' && s[i] <= 'z') ;
            else even = false;
        }
        if(!(i & 1))
        {
            if(s[i] >= 'A' && s[i] <= 'Z') ;
            else odd = false;
        }
    }
    if(even && odd) cout << "Yes" << endl;
    else cout << "No" << endl;
}
int main()
{
    ios
    bool multi = 0;   // 0 for single and 1 for multi
    if(multi) cin >> t;
    else t = 1;
    while(t--)
    {
        solve();
    }
}