import java.util.*; import java.io.*; public class Main { static long mod = 998244353; static int INF = 1000000000; public static void main(String[] args){ FastScanner scanner = new FastScanner(); String s = scanner.next(); String t = " "; t += s; int n = t.length(); for(int i = 0; i < n; i++){ if(i % 2 == 0 && t.charAt(i) != ' '){ System.out.println("No"); return; }else if(i % 2 == 1 && t.charAt(i) == ' '){ System.out.println("No"); return; } } System.out.println("Yes"); return; } static class BIT{ int n; int[] bit; public BIT(int n){ this.n = n; bit = new int[n+1]; } void add(int idx, int val){ for(int i = idx+1; i <= n; i += i&(-i)) bit[i-1] += val; } int sum(int idx){ int res = 0; for(int i = idx+1; i > 0; i -= i&(-i)) res += bit[i-1]; return res; } int sum(int begin, int end){ if(begin == 0) return sum(end); return sum(end)-sum(begin-1); } } static class Pair implements Comparable{ int first, second; Pair(int a, int b){ first = a; second = b; } @Override public boolean equals(Object o){ if (this == o) return true; if (!(o instanceof Pair)) return false; Pair p = (Pair) o; return first == p.first && second == p.second; } @Override public int compareTo(Pair p){ //return first == p.first ? second - p.second : first - p.first; //firstで昇順にソート //return (first == p.first ? second - p.second : first - p.first) * -1; //firstで降順にソート //return second == p.second ? first - p.first : second - p.second;//secondで昇順にソート //return (second == p.second ? first - p.first : second - p.second)*-1;//secondで降順にソート //return first * 1.0 / second > p.first * 1.0 / p.second ? 1 : -1; // first/secondの昇順にソート //return first * 1.0 / second < p.first * 1.0 / p.second ? 1 : -1; // first/secondの降順にソート //return second * 1.0 / first > p.second * 1.0 / p.first ? 1 : -1; // second/firstの昇順にソート //return second * 1.0 / first < p.second * 1.0 / p.first ? 1 : -1; // second/firstの降順にソート //return Math.atan2(second, first) > Math.atan2(p.second, p.first) ? 1 : -1; // second/firstの昇順にソート //return first + second > p.first + p.second ? 1 : -1; //first+secondの昇順にソート //return first + second < p.first + p.second ? 1 : -1; //first+secondの降順にソート //return first - second < p.first - p.second ? 1 : -1; //first-secondの降順にソート return Math.atan2(second,first) > Math.atan2(p.second, p.first) ? 1 : -1; } } private static class FastScanner { private final InputStream in = System.in; private final byte[] buffer = new byte[1024]; private int ptr = 0; private int buflen = 0; private boolean hasNextByte() { if (ptr < buflen) { return true; }else{ ptr = 0; try { buflen = in.read(buffer); } catch (IOException e) { e.printStackTrace(); } if (buflen <= 0) { return false; } } return true; } private int readByte() { if (hasNextByte()) return buffer[ptr++]; else return -1;} private static boolean isPrintableChar(int c) { return 33 <= c && c <= 126;} public boolean hasNext() { while(hasNextByte() && !isPrintableChar(buffer[ptr])) ptr++; return hasNextByte();} public String next() { if (!hasNext()) throw new NoSuchElementException(); StringBuilder sb = new StringBuilder(); int b = readByte(); while(isPrintableChar(b)) { sb.appendCodePoint(b); b = readByte(); } return sb.toString(); } public long nextLong() { if (!hasNext()) throw new NoSuchElementException(); long n = 0; boolean minus = false; int b = readByte(); if (b == '-') { minus = true; b = readByte(); } if (b < '0' || '9' < b) { throw new NumberFormatException(); } while(true){ if ('0' <= b && b <= '9') { n *= 10; n += b - '0'; }else if(b == -1 || !isPrintableChar(b)){ return minus ? -n : n; }else{ throw new NumberFormatException(); } b = readByte(); } } public int nextInt() { long nl = nextLong(); if (nl < Integer.MIN_VALUE || nl > Integer.MAX_VALUE) throw new NumberFormatException(); return (int) nl; } public double nextDouble() { return Double.parseDouble(next());} } }