source_code: import java.io.OutputStream;
  import java.io.IOException;
  import java.io.InputStream;
  import java.io.PrintWriter;
  import java.util.Arrays;
  import java.util.InputMismatchException;
  import java.io.IOException;
  import java.util.ArrayList;
  import java.io.InputStream;
  
  /**
   * Built using CHelper plug-in
   * Actual solution is at the top
   */
  public class Main {
    public static void main(String[] args) {
      InputStream inputStream = System.in;
      OutputStream outputStream = System.out;
      InputReader in = new InputReader(inputStream);
      PrintWriter out = new PrintWriter(outputStream);
      TaskC solver = new TaskC();
      solver.solve(1, in, out);
      out.close();
    }
  
    static class TaskC {
      private long MOD = (long) (1e9 + 7);
      int[][] dp = new int[5001][5001];
  
      public void solve(int testNumber, InputReader in, PrintWriter out) {
        int n = in.nextInt();
        ArrayList<Character> commands = new ArrayList<>();
  
        for (int i = 0; i < n; i++) {
          char ch = in.next().charAt(0);
          commands.add(ch);
        }
        for (int a[] : dp) Arrays.fill(a, -1);
  
        out.println(count(0, commands, 0));
  
      }
  
      public int count(int index, ArrayList<Character> commands, int deepCount) {
        if (deepCount < 0) {
          return 0;
        }
        if (index == commands.size()) {
          return 1;
        } else {
  
          if (dp[index][deepCount] != -1) return dp[index][deepCount];
          long result = 0;
          char ch = commands.get(index);
          result = count(index, commands, deepCount - 1);
          if (ch == 's') {
            result += count(index + 1, commands, deepCount);
          } else {
            result += count(index + 1, commands, deepCount + 1);
            result -= count(index + 1, commands, deepCount);
          }
          if (result >= MOD) {
            result -= MOD;
          }
          if (result < 0) {
            result += MOD;
          }
          return dp[index][deepCount] = (int) result;
        }
      }
  
    }
  
    static class InputReader {
      private InputStream stream;
      private byte[] buf = new byte[1024];
      private int curChar;
      private int numChars;
      private InputReader.SpaceCharFilter filter;
  
      public InputReader(InputStream stream) {
        this.stream = stream;
      }
  
      public int read() {
        if (numChars == -1) {
          throw new InputMismatchException();
        }
        if (curChar >= numChars) {
          curChar = 0;
          try {
            numChars = stream.read(buf);
          } catch (IOException e) {
            throw new InputMismatchException();
          }
          if (numChars <= 0) {
            return -1;
          }
        }
        return buf[curChar++];
      }
  
      public int readInt() {
        int c = read();
        while (isSpaceChar(c)) {
          c = read();
        }
        int sgn = 1;
        if (c == '-') {
          sgn = -1;
          c = read();
        }
        int res = 0;
        do {
          if (c < '0' || c > '9') {
            throw new InputMismatchException();
          }
          res *= 10;
          res += c - '0';
          c = read();
        } while (!isSpaceChar(c));
        return res * sgn;
      }
  
      public String readString() {
        int c = read();
        while (isSpaceChar(c)) {
          c = read();
        }
        StringBuilder res = new StringBuilder();
        do {
          if (Character.isValidCodePoint(c)) {
            res.appendCodePoint(c);
          }
          c = read();
        } while (!isSpaceChar(c));
        return res.toString();
      }
  
      public boolean isSpaceChar(int c) {
        if (filter != null) {
          return filter.isSpaceChar(c);
        }
        return isWhitespace(c);
      }
  
      public static boolean isWhitespace(int c) {
        return c == ' ' || c == '\n' || c == '\r' || c == '\t' || c == -1;
      }
  
      public String next() {
        return readString();
      }
  
      public int nextInt() {
        return readInt();
      }
  
      public interface SpaceCharFilter {
        public boolean isSpaceChar(int ch);
  
      }
  
    }
  }
  
  