#include<bits/stdc++.h>
using namespace std;
#define fs first
#define sc second
#define pb push_back
#define mp make_pair
#define eb emplace_back
#define ALL(A) A.begin(),A.end()
#define RALL(A) A.rbegin(),A.rend()
typedef long long LL;
typedef pair<LL,LL> P;
LL mod=1000000007;
LL LINF=1LL<<60;
const int INF=1<<30;
int dx[]={1,0,-1,0};
int dy[]={0,1,0,-1};



int main(){
    string s;
    getline(cin,s);
    for (int i = 0; i < s.length(); i++) {
        if(i%2){
            if(s[i]!=' '){
                puts("No");
                return 0;
            }
        }
        else{
            if(s[i]==' '){
                puts("No");
                return 0;
            }
        }
    }
    puts("Yes");
    return 0;
}