#include<bits/stdc++.h>
#include<fstream>
using namespace std;  
#define ll long long int
#define all(x) begin(x), end(x) 
bool isPowerOfTwo (int x) {  
    return x && (!(x&(x-1))); 
} 
int main(){ 
    //std::ios_base::sync_with_stdio(0);
    //std::cin.tie(0);
    //freopen("king2.in", "r", stdin);
    //freopen("king2.out", "w", stdout); 
    std::string s;
    std::cin >> s;
    int od = 0, ev = 0;
    bool f = false;
    for(int i = 0; i < (int)s.size(); i++){
        if((i+1)%2 != 0){
            if(s[i] >= 97 && s[i] <= 122){ 
                 od++;
                 continue;
            }
            else{
               f = true; 
                break;
            }
        }
        if((i+1)%2 == 0){
            if(s[i] >= 65 && s[i] <= 90){
                ev++;
                continue;
            }
            else{
               f = true; 
               break;
           }
        } 
        else{
            f = true; 
            break;
        }
    }
    if(f == false){
        std::cout <<"Yes\n";
    }
    else{
        std::cout << "No\n";
    }
}
#include <bits/stdc++.h>
using namespace std;
template <class T> inline bool chmax(T &a, T b) {
    if(a < b) {
        a = b;
        return 1;
    }
    return 0;
}
template <class T> inline bool chmin(T &a, T b) {
    if(a > b) {
        a = b;
        return 1;
    }
    return 0;
}
#define DEBUG
#ifdef DEBUG
template <class T, class U>
ostream &operator<<(ostream &os, const pair<T, U> &p) {
    os << '(' << p.first << ',' << p.second << ')';
    return os;
}
template <class T> ostream &operator<<(ostream &os, const vector<T> &v) {
    os << '{';
    for(int i = 0; i < (int)v.size(); i++) {
        if(i) { os << ','; }
        os << v[i];
    }
    os << '}';
    return os;
}
void debugg() { cerr << endl; }
template <class T, class... Args>
void debugg(const T &x, const Args &... args) {
    cerr << " " << x;
    debugg(args...);
}
#define debug(...)                                                             \
    cerr << __LINE__ << " [" << #__VA_ARGS__ << "]: ", debugg(__VA_ARGS__)
#define dump(x) cerr << __LINE__ << " " << #x << " = " << (x) << endl
#else
#define debug(...) (void(0))
#define dump(x) (void(0))
#endif

struct Setup {
    Setup() {
        cin.tie(0);
        ios::sync_with_stdio(false);
        cout << fixed << setprecision(15);
    }
} __Setup;

using ll = long long;
#define ALL(v) (v).begin(), (v).end()
#define RALL(v) (v).rbegin(), (v).rend()
#define FOR(i, a, b) for(int i = (a); i < int(b); i++)
#define REP(i, n) FOR(i, 0, n)
const int INF = 1 << 30;
const ll LLINF = 1LL << 60;
constexpr int MOD = 1000000007;
const int dx[4] = {1, 0, -1, 0};
const int dy[4] = {0, 1, 0, -1};

//-------------------------------------

int main() {
    string s; cin >> s;


    bool ok = true;
    REP(i, s.size()){
        if(i % 2 == 0 && !('a' <= s[i] && s[i] <= 'z')){
            ok = false;
        }else if(i % 2 && !('A' <= s[i] && s[i] <= 'Z')){
            ok = false;
        }
    }

    cout << (ok ? "Yes" : "No") << endl;
}