#include<bits/stdc++.h>

using namespace std;
using ll=long long;
#define rep2(i, a, n) for(int i = (a); i < (n); i++)
#define rep(i, n) rep2(i,0,n)

int main(){
  cin.tie(nullptr);ios_base::sync_with_stdio(false);
  string s;
  //$BA4$F$N4q?tHVL\$NJ8;z$,1Q>.J8;z$G!"A4$F$N6v?tHVL\$NJ8;z$,H>3Q%9%Z!<%9(B
  getline(cin,s);
  bool flag=true;
  for(int i=0;s[i]!='\n';i++){
    //cout<<i<<" "<<s[i]<<endl;
    if(i%2==0&&!(s[i]>='a'&&s[i]<='z')){
      flag=false;
      break;
    }
    if(i%2==1&&s[i]!=' '){
      flag=false;
      break;
    }
  }
  cout<<(flag?"Yes":"No")<<endl;
}