#include <stdio.h>
#include <iostream>
#include <cmath>
#include <iomanip>
#include <sstream>
#include <string>
#include <vector>
#include <stack>
#include <algorithm>
#include <map>
#include <string>
#include <queue>
#include <list>
#include <set>
#include <ctime>
#include <queue>
#include <cstring>
#include <bitset>
#include <unordered_map>
#include <unordered_set>
using namespace std;
typedef long long ll;
typedef long double ld;
typedef unsigned long long ull;
const ll INF = 0x3f3f3f3f3f3f;
int main()
{
    bool flag = true;
    string s;
    cin >> s;
    for (ll i = 0; i < s.size(); i++)
    {
        if (i % 2 == 0 && s[i] >= 'A' && s[i] <= 'Z')
        {
            flag = false;
        }
        if (i % 2 == 1 && s[i] >= 'a' && s[i] <= 'z')
        {
            flag = false;
        }
    }
    if (flag)
    {
        cout << "Yes" << endl;
    }
    else
    {
        cout << "No" << endl;
    }
    return 0;
}
#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;
}