#include<iostream>
#include<vector>
#include<algorithm>
#include<functional>
#include<queue>
#include<stack>
#include<set>
#include<map>
#include<unordered_map>
#include<climits>
#include<cstdlib>
#include<cmath>
#include<string>
#include<iomanip>
#include<bitset>
#include<list>

using namespace std;

#define ll long long int

ll const MOD = 1000000007;
ll const INF = (long long int)1 << 61;

ll mypow(ll x,ll n,ll mod = MOD){
    ll ret = 1;
    while(n > 0){
        if(n&1){
            ret = (ret*x)%mod;
        }
        x = (x*x)%mod;
        n >>= 1;
    }
    return ret;
}

ll mygcd(ll a,ll b){
    if(b == 0)return a;
    return mygcd(b,a%b);
}

ll twoPow(ll shiftNum){
    return (1LL << (shiftNum - 1));
}

int main(){
    cin.tie(0);
    ios::sync_with_stdio(false);
 
    string str;
    cin >> str;

    for(int i = 0; i < str.size(); i+=2){
        if('a' <= str[i] && str[i] <= 'z'){

        }else{
            cout << "No" << endl;
            return 0;
        }
    }

    cerr << 'O' << endl;

    for(int i = 1; i < str.size(); i += 2){
        if(str[i] != ' '){
            cout << "No" << endl;
            return 0;
        }
    }

    cout << "Yes" << endl;

    return 0;
}