Problem:
Score : 300 points

Problem Statement

You are given a string S consisting of lowercase English letters.
Another string T is initially empty.
Determine whether it is possible to obtain S = T by performing the following operation an arbitrary number of times:

Append one of the following at the end of T: dream, dreamer, erase and eraser.

Constraints

1≦|S|≦10^5

S consists of lowercase English letters.

Input

The input is given from Standard Input in the following format:

S

Output

If it is possible to obtain S = T, print YES. Otherwise, print NO.

Sample Input 1

erasedream

Sample Output 1

YES

Append erase and dream at the end of T in this order, to obtain S = T.

Sample Input 2

dreameraser

Sample Output 2

YES

Append dream and eraser at the end of T in this order, to obtain S = T.

Sample Input 3

dreamerer

Sample Output 3

NO

Solution in JavaScript (node.js v5.12) (judge verdict: Accepted)

module.exports=function(e){var r={};function n(t){if(r[t])return r[t].exports;var o=r[t]={i:t,l:!1,exports:{}};return e[t].call(o.exports,o,o.exports,n),o.l=!0,o.exports}return n.m=e,n.c=r,n.d=function(e,r,t){n.o(e,r)||Object.defineProperty(e,r,{enumerable:!0,get:t})},n.r=function(e){"undefined"!=typeof Symbol&&Symbol.toStringTag&&Object.defineProperty(e,Symbol.toStringTag,{value:"Module"}),Object.defineProperty(e,"__esModule",{value:!0})},n.t=function(e,r){if(1&r&&(e=n(e)),8&r)return e;if(4&r&&"object"==typeof e&&e&&e.__esModule)return e;var t=Object.create(null);if(n.r(t),Object.defineProperty(t,"default",{enumerable:!0,value:e}),2&r&&"string"!=typeof e)for(var o in e)n.d(t,o,function(r){return e[r]}.bind(null,o));return t},n.n=function(e){var r=e&&e.__esModule?function(){return e.default}:function(){return e};return n.d(r,"a",r),r},n.o=function(e,r){return Object.prototype.hasOwnProperty.call(e,r)},n.p="",n(n.s=0)}([function(e,r,n){n(1)(n(2).readFileSync("/dev/stdin","UTF-8"))},function(e,r){e.exports=function(e){for(var r=e.split("\n")[0],n="",t=["dream","dreamer","erase","eraser"],o=r.length-1;o>=0;o--){n=r[o]+n;for(var u=!1,i=0;i<4;i++)n==t[i]&&(n="",u=!0);if(!u&&n.length>=7)return void console.log("NO")}""==n?console.log("YES"):console.log("NO")}},function(e,r){e.exports=require("fs")}]);