class Problem0908:
    def solve(this):
        s = input()

        
        for i,c in enumerate(s):
            if i % 2 == 0 and c.islower() == False:
                print("No")
                return
            elif i % 2 == 1 and c != " ":
                print("No")
                return
        print("Yes")

if __name__ == "__main__":
    problem = Problem0908()
    problem.solve()