import std;

bool calc(string s) {
    for (int i = 0; i < s.length; i++) {
        if (i % 2 == 0 && s[i] == ' ') return false;
        if (i % 2 == 1 && s[i] != ' ') return false;
    }
    return true;
}

void main() {
    string s = read!string;
    writeln(calc(s) ? "Yes" : "No");
}

void scan(T...)(ref T a) {
    string[] ss = readln.split;
    foreach (i, t; T) a[i] = ss[i].to!t;
}
T read(T)() { return readln.chomp.to!T; }
T[] reads(T)() { return readln.split.to!(T[]); }
alias readint = read!int;
alias readints = reads!int;