import java.io.BufferedInputStream;
import java.io.IOException;
import java.io.InputStream;
import java.util.Arrays;

class Main {
	public static void main(String[] args) throws IOException {
		Scanner sc = new Scanner(System.in);
		String S = sc.next();

		int position = 0;
		int prev = 0;
		while (position < S.length()) {
			String current = S.substring(position, Math.min(position + 5, S.length()));
			// debug(current);
			if (current.startsWith("dream")) {
				position += "dream".length();
				prev = 1;
			} else if (current.startsWith("er")) {
				position += "er".length();
				if (prev == 2) {
					prev = 4;
				} else {
					prev = 2;
				}
			} else if (current.startsWith("aser")) {
				if (prev != 2 && prev != 4) {
					System.out.println("NO");
					return;
				}
				position += "aser".length();
				prev = 3;
			} else if (current.startsWith("ase")) {
				if (prev != 2 && prev != 4) {
					System.out.println("NO");
					return;
				}
				position += "ase".length();
				prev = 3;
			} else {
				System.out.println("NO");
				return;
			}
		}

		if (prev == 4) {
			System.out.println("NO");
		} else {
			System.out.println("YES");
		}
	}

	private static boolean isDebug = System.getProperty("sun.desktop") != null;

	private static void debug(Object... o) {
		if (isDebug) {
			System.err.println(Arrays.deepToString(o));
		}
	}

	public static class Scanner {
		private BufferedInputStream inputStream;

		public Scanner(InputStream in) {
			inputStream = new BufferedInputStream(in);
		}

		public int nextInt() throws IOException {
			int num = 0;

			int read = skip();
			do {
				num = num * 10 + (read - 0x30);
			} while ((read = inputStream.read()) > 0x20);

			return num;
		}

		public void fill(int[] a) throws IOException {
			for (int i = 0; i < a.length; i++) {
				a[i] = nextInt();
			}
		}

		public void fill(int[] a, int[] b) throws IOException {
			if (a.length != b.length) {
				throw new IllegalArgumentException();
			}

			for (int i = 0; i < a.length; i++) {
				a[i] = nextInt();
				b[i] = nextInt();
			}
		}

		public long nextLong() throws IOException {
			long num = 0;

			int read = skip();
			do {
				num = num * 10 + (read - 0x30);
			} while ((read = inputStream.read()) > 0x20);

			return num;
		}

		public void fill(long[] a) throws IOException {
			for (int i = 0; i < a.length; i++) {
				a[i] = nextLong();
			}
		}

		public void fill(long[] a, long[] b) throws IOException {
			if (a.length != b.length) {
				throw new IllegalArgumentException();
			}

			for (int i = 0; i < a.length; i++) {
				a[i] = nextLong();
				b[i] = nextLong();
			}
		}

		public long[] nextLong(int n) throws IOException {
			long[] array = new long[n];
			for (int i = 0; i < n; i++) {
				array[i] = nextLong();
			}

			return array;
		}

		public String next() throws IOException {
			StringBuilder builder = new StringBuilder();

			int read = skip();
			do {
				builder.append((char) read);
			} while ((read = inputStream.read()) > 0x20);

			return builder.toString();
		}

		private int skip() throws IOException {
			int read;
			while ((read = inputStream.read()) <= 0x20)
				;

			return read;
		}
	}
}


Measured memory_bytes: 10964