source_code: 
  
  import java.io.BufferedReader;
  import java.io.IOException;
  import java.io.InputStream;
  import java.io.InputStreamReader;
  import java.util.Arrays;
  import java.util.StringTokenizer;
  
  public class C {
  
  	//dp[firstInLoop][index][indentLevel]
  	private static int[][][] dp;
  	private static boolean[] wasLoop;
  	private static int MOD=1000000007;
  	private static int n;
  	
  	public static void solve(FastScanner fs) {	
  		n=fs.nextInt();
  		dp=new int[2][n][n];
  		for (int i=0; i<dp.length; i++)
  			for (int j=0; j<dp[i].length; j++)
  				Arrays.fill(dp[i][j], -1);
  		wasLoop=new boolean[n];
  		for (int i=0; i<n; i++)
  			wasLoop[i]=fs.next().equals("f");
  		
  		int ans=go(0, 0, 0);
  		System.out.println(ans);
  	}
  	
  	private static int go(int firstInLoop, int index, int indentLevel) {
  		if (index>=n)//base case
  			return 1;
  		if (dp[firstInLoop][index][indentLevel]!=-1)
  			return dp[firstInLoop][index][indentLevel];
  		
  		//if I am forced, just do it
  		if (firstInLoop==1)
  			return dp[firstInLoop][index][indentLevel]=go(wasLoop[index]?1:0, index+1, indentLevel+(wasLoop[index]?1:0));
  		
  		//if I am on the end level, I don't have a choice
  		if (indentLevel==0) {
  			return dp[firstInLoop][index][indentLevel]=go(wasLoop[index]?1:0, index+1, wasLoop[index]?1:0);
  		}
  		else {
  			//otherwise, add all the possibilities
  			int total=0;
  			total+=go(firstInLoop, index, indentLevel-1);
  			total+=go(wasLoop[index]?1:0, index+1, indentLevel+(wasLoop[index]?1:0));
  			total%=MOD;
  			return dp[firstInLoop][index][indentLevel]=total;
  		}
  	}
  
  	
  	
  	
  	
  	public static void main(String[] args) throws NumberFormatException, IOException {
  		FastScanner scanner = new FastScanner(System.in);
  		solve(scanner);
  	}
  	
  
  	private static class FastScanner {
  		BufferedReader br;
  		StringTokenizer st;
  		public FastScanner(InputStream in) {
  			br = new BufferedReader(new InputStreamReader(in));
  		}
  		String next() {
  			while (st == null || !st.hasMoreElements()) {
  				try {
  					st = new StringTokenizer(br.readLine());
  				} catch (IOException e) {
  					e.printStackTrace();
  				}
  			}
  			return st.nextToken();
  		}
  		int nextInt() {
  			return Integer.parseInt(next());
  		}
  		long nextLong() {
  			return Long.parseLong(next());
  		}
  		double nextDouble() {
  			return Double.parseDouble(next());
  		}
  		String nextLine() {
  			String str = "";
  			try {
  				str = br.readLine();
  			} catch (IOException e) {
  				e.printStackTrace();
  			}
  			return str;
  		}
  		int[] readArray(int n) {
  			int[] a=new int[n];
  			for (int i=0; i<n; i++)
  				a[i]=nextInt();
  			return a;
  		}
  	}
  }
  
  
  