#include <stdio.h>
#include <stdlib.h>
#include <string.h>

int main(){
   char s[100];
   int flag = 0;
   fgets(s,100,stdin);
   for(int i = 0;i < strlen(s);i++){
      if((i%2 == 1)&&(s[i] != " "))flag = 1;
      else if((i%2 == 0)&&!(s[i] >= 97)&&!(s[i] <= 122))flag = 1;
   }
   if(flag == 1)printf("No\n");
   else printf("Yes\n");
}