#define _CRT_SECURE_NO_WARNINGS
#include<iostream>
#include<algorithm>
#include<math.h>
#include<string>
using namespace std;
const int N = 1e8 + 10;
typedef long long ll;
int main(){
	int n,m,t,k,ans;
	string s;
//	cin>>t;
//	while(t--){
		cin>>s;
		int ok=1;
		for(int i=0;i<s.size()&&ok;i++){
			if(i%2==0&&(s[i]<'a'||s[i]>'z'))ok=0;
			if(i%2==1&&(s[i]<'A'||s[i]>'Z'))ok=0;
		}
		if(ok)cout<<"Yes\n";
		else cout<<"No\n";
//	}
	return 0;
}


#include<bits/stdc++.h>
#include<ext/pb_ds/assoc_container.hpp>
#include<ext/pb_ds/tree_policy.hpp>
#define fast_az_fuk ios_base::sync_with_stdio(false); cin.tie(NULL); cout.tie(NULL);
#define ll long long 
#define ull unsigned ll
#define ld long double 
#define pb push_back 
#define pf push_front
#define dll deque<ll> 
#define vll vector<ll>
#define vvll vector<vll> 
#define pll pair<ll,ll> 
#define vpll vector<pll>
#define dpll deque<pll>
#define mapll map<ll,ll>
#define umapll umap<ll,ll>
#define endl "\n" 
#define all(v) v.begin(),v.end() 
#define ms(a,x) memset(a,x,sizeof(a))
#define ordered_set tree<ll, null_type,less<ll>, rb_tree_tag,tree_order_statistics_node_update>
using namespace std;
using namespace __gnu_pbds;
vector<string> split(const string& s, char c) {
    vector<string> v; stringstream ss(s); string x;
    while (getline(ss, x, c)) v.push_back(x); return move(v);
}
template<typename T, typename... Args>
inline string arrStr(T arr, int n) {
    stringstream s; s << "[";
    for(int i = 0; i < n - 1; i++) s << arr[i] << ",";
    s << arr[n - 1] << "]";
    return s.str();
}
#define EVARS(args...) {__evars_begin(__LINE__); __evars(split(#args, ',').begin(), args);}
inline void __evars_begin(int line) { cerr << "#" << line << ": "; }
template<typename T> inline void __evars_out_var(vector<T> val) { cerr << arrStr(val, val.size()); }
template<typename T> inline void __evars_out_var(T* val) { cerr << arrStr(val, 10); }
template<typename T> inline void __evars_out_var(T val) { cerr << val; }
inline void __evars(vector<string>::iterator it) { cerr << endl; }
template<typename T, typename... Args>
inline void __evars(vector<string>::iterator it, T a, Args... args) {
    cerr << it->substr((*it)[0] == ' ', it->length()) << "=";
    __evars_out_var(a);
    cerr << "; ";
    __evars(++it, args...);
}
struct custom_hash {
    static uint64_t splitmix64(uint64_t x) {
        // http://xorshift.di.unimi.it/splitmix64.c
        x += 0x9e3779b97f4a7c15;
        x = (x ^ (x >> 30)) * 0xbf58476d1ce4e5b9;
        x = (x ^ (x >> 27)) * 0x94d049bb133111eb;
        return x ^ (x >> 31);
    }

    size_t operator()(uint64_t x) const {
        static const uint64_t FIXED_RANDOM = chrono::steady_clock::now().time_since_epoch().count();
        return splitmix64(x + FIXED_RANDOM);
    }
};
template<class T, class H>using umap=unordered_map<T,H,custom_hash>;
template<class T>using uset=unordered_set<T,custom_hash>;
bool isLoweCase(char c){
    return (c-'a'>=0);
}
int32_t main()
{
    clock_t clk = clock();
    fast_az_fuk
    string s; cin>>s; ll n = s.length();
    bool isUnreadable=1;
    for(ll i=0;i<n;i+=2){
        if(!isLoweCase(s[i])) {isUnreadable=0; break;}
    }
    if(!isUnreadable) {cout<<"No\n"; return 0;}
    for(ll i=1;i<n;i+=2){
        if(isLoweCase(s[i])) { isUnreadable=0; break;}
    }
    if(!isUnreadable) cout<<"No\n"; else cout<<"Yes\n";
    // cerr << '\n'<<"Time (in s): " << double(clock() - clk) * 1.0 / CLOCKS_PER_SEC << '\n';
    return 0;
}