#include <bits/stdc++.h>
using namespace std;
#define rep(i,n) for(int i=0;i<(int)(n);i++)
#define all(vec) vec.begin(),vec.end()
#define MOD 1000000007
#define int long long

signed main(){
    string s;cin>>s;
    for(int i=1;i<s.size();i+=2)if(s[i]!=' '){cout<<"No"<<endl;return 0;}
    cout<<"Yes"<<endl;
}