codeparrot/codecomplex huggingface dataset:
// Problem: 909_C. Python Indentation
// Time complexity: quadratic
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 C455 {
	static int N;
	static final int mod = 1_000_000_007;
	static int[][] memo;
	static int[] list;
	public static void main(String[] args) {
		FS scan = new FS(System.in);
		
		N = scan.nextInt();
		list = new int[N];
		for(int i=0;i<N;i++) {
			list[i] = scan.next().equals("s")?0:1;
		}
		if(list[N-1] == 1) {
			System.out.println(0);
			return;
		}
		memo = new int[N+1][N+2];
		Arrays.fill(memo[N], 1);
		int[] sum = new int[N+2];
		
		for(int i=N-1;i>=0;i--) {
			sum[0] = memo[i+1][0];
			for(int j=1;j<sum.length;j++) {
				sum[j] = sum[j-1] + memo[i+1][j];
				sum[j] %= mod;
			}
			for(int j=0;j<=N;j++) {
				if (list[i]==1 && (i==0 || list[i-1]==1))
					memo[i][j] = memo[i+1][j+1];
				else if(i==0 || list[i-1] == 1)
					memo[i][j] = memo[i+1][j];
				else if (list[i]==1){
//					for(int k=0;k<=j;k++) {
//						memo[i][j] += memo[i+1][k+1];
//					}
					memo[i][j] = sum[j+1] - sum[0] + mod;
					memo[i][j] %= mod;
					
				}
				else if (list[i]==0) {
					memo[i][j] = sum[j];
				}
			}
		}
		
//		for(int i=0;i<=N;i++) {
//			for(int j=0;j<=N;j++) {
//				System.out.print(memo[i][j]+" ");
//			}
//			System.out.println();
//		}
//		System.out.println();
		System.out.println(memo[0][0]);
	}
	
	private static class FS {
		BufferedReader br;
		StringTokenizer st;
		public FS(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());}
	}
}
// Problem: 909_C. Python Indentation
// Time complexity: quadratic

import java.io.*;
import java.math.*;
import java.util.*;


public class Main {
    private static final int MAX = 5000 + 10,mod = 1000000007;
    private static char [] S;
    private static int n;
    private static Integer [] [] dp = new Integer[MAX][MAX];

    private static int solve(int pos,int open){
        if(pos == n) return (open == 0) ? 1 : 0;
        if (dp[pos][open] != null) return dp[pos][open];
        int res = 0;
        if (S[pos] == 's') {
            res = solve(pos + 1,open);
            if (open > 0) res += solve(pos,open - 1);
            if (res >= mod) res -= mod;
        }
        else {
            res = solve(pos+1,open + 1);
        }
        return dp[pos][open] = res;
    }

    public static void main(String[] args) throws Exception{
        IO io = new IO(null,null);
        n = io.getNextInt();
        S = new char[n];
        for (int i = 0;i < n;i++) S[i] = io.getNext().charAt(0);
        io.println(solve(0,0));
        io.close();
    }
}



class IO{
    private BufferedReader br;
    private StringTokenizer st;
    private PrintWriter writer;
    private String inputFile,outputFile;

    public boolean hasMore() throws IOException{
        if(st != null && st.hasMoreTokens()) return true;
        if(br != null && br.ready()) return true;
        return false;
    }
    public String getNext() throws FileNotFoundException, IOException{
        while(st == null || !st.hasMoreTokens()) st = new StringTokenizer(br.readLine());
        return st.nextToken();
    }

    public String getNextLine() throws FileNotFoundException, IOException{
        return br.readLine().trim();
    }

    public int getNextInt() throws FileNotFoundException, IOException{
        return Integer.parseInt(getNext());
    }
    public long getNextLong() throws FileNotFoundException, IOException{
        return Long.parseLong(getNext());
    }

    public void print(double x,int num_digits) throws  IOException{
        writer.printf("%." + num_digits + "f" ,x);
    }
    public void println(double x,int num_digits) throws  IOException{
        writer.printf("%." + num_digits + "f\n" ,x);
    }
    public void print(Object o) throws  IOException{
        writer.print(o.toString());
    }

    public void println(Object o) throws  IOException{
        writer.println(o.toString());
    }
    public IO(String x,String y) throws FileNotFoundException, IOException{
        inputFile = x;
        outputFile = y;
        if(x != null) br = new BufferedReader(new FileReader(inputFile));
        else br = new BufferedReader(new InputStreamReader(System.in));
        if(y != null) writer = new PrintWriter(new BufferedWriter(new FileWriter(outputFile)));
        else writer = new PrintWriter(new OutputStreamWriter(System.out));
    }

    protected void close() throws IOException{
        br.close();
        writer.close();
    }
}
// Problem: 909_C. Python Indentation
// Time complexity: quadratic
import java.util.ArrayList;
import java.util.List;
import java.util.Scanner;

/**
 * Created by Jarek on 2017-12-30.
 */
public class PhytonIndenter {

    private static Scanner scanner = new Scanner(System.in);

    private static int lineCount;
    private static String[] commands;

    public static void main(String args[]) {
        lineCount = scanner.nextInt();
        scanner.nextLine();
        commands = new String[lineCount];

        for (int i = 0; i < lineCount; i++) {
            commands[i] = scanner.nextLine();
        }

        resolveWithDP();
    }

    private static void resolveWithDP() {
        long dp[][] = new long[lineCount][5002];
        long mod = 1000000007;
        dp[0][0] = 1;
        for (int i = 1; i < lineCount; i++) {
            if ("f".equalsIgnoreCase(commands[i - 1])) {
                dp[i][0] = 0;
                for (int j = 1; j <= i; j++) {
                    dp[i][j] = dp[i - 1][j - 1];
                }
            } else {
                long sum = 0;
                for (int j = i - 1; j >= 0; j--) {
                    sum += dp[i - 1][j] % mod;
                    dp[i][j] = sum;
                }
            }
        }

        long result = 0;
        for (int i = 0; i < lineCount; i++) {
            result += dp[lineCount-1][i]%mod;
            result %= mod;
        }
        System.out.println(result%mod);
    }

}
// Problem: 909_C. Python Indentation
// Time complexity: quadratic
import java.io.OutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.PrintWriter;
import java.util.List;
import java.util.StringTokenizer;
import java.io.IOException;
import java.io.BufferedReader;
import java.util.Collections;
import java.io.InputStreamReader;
import java.util.ArrayList;
import java.io.InputStream;

public class C909 {
    public static void main(String[] args) {
        InputStream inputStream = System.in;
        OutputStream outputStream = System.out;
        InputReader in = new InputReader(inputStream);
        PrintWriter out = new PrintWriter(outputStream);
        TaskA solver = new TaskA();
        solver.solve(1, in, out);
        out.close();
    }

    static class TaskA {
        public void solve(int testNumber, InputReader in, PrintWriter out) {
            int n = in.nextInt();
            int ar[] = new int[n+1];
            int count = 1;
            ar[0] = 1;
            for(int i=0;i<n;i++){
                char c = in.next().charAt(0);
                if(c == 'f')
                    count++;
                else{
                    for(int j=1;j<count;j++){
                        ar[j] = (ar[j] + ar[j-1])% (int)(1e9+7);
                    }
                }    
            }
            out.println(ar[count-1]);
        }
    }

    static class InputReader {
        public BufferedReader reader;
        public StringTokenizer tokenizer;

        public InputReader(InputStream stream) {
            reader = new BufferedReader(new InputStreamReader(stream), 32768);
            tokenizer = null;
        }

        public String next() {
            while (tokenizer == null || !tokenizer.hasMoreTokens()) {
                try {
                    tokenizer = new StringTokenizer(reader.readLine());
                } catch (IOException e) {
                    throw new RuntimeException(e);
                }
            }
            return tokenizer.nextToken();
        }

        public int nextInt() {
            return Integer.parseInt(next());
        }

        public long nextLong() {
            return Long.parseLong(next());
        }

        public double nextDouble() {
            return Double.parseDouble(next());
        }

        public String nextLine() {
            String str = "";
            try
            {
                str = reader.readLine();
            }
            catch (IOException e)
            {
                e.printStackTrace();
            }
            return str;
        }
    }
}
// Problem: 909_C. Python Indentation
// Time complexity: quadratic
import java.io.*;
import java.nio.file.Files;
import java.nio.file.Paths;
import java.util.*;

public class Main {

    public static void main(String[] args) {

        solve(System.in,System.out);

    }

    static void solve(InputStream inStream, PrintStream printStream) {
        Scanner in = new Scanner(inStream);
        int n = in.nextInt();
        long[] sums = new long[n];
        for (int i = 1; i < n; i++) {
            sums[i]=0;
        }
        sums[0]=1;

        long mod = 1000000007;

        for (int i = 0; i < n; i++) {
            if (in.next().equals("f") ) {
                for (int j = n-1; j > 0 ; j--) {
                    sums[j]=sums[j-1];
                }
                sums[0]=0;
            } else {
                for (int j = n-2; j >= 0 ; j--) {
                    sums[j] += sums[j+1];
                    if (sums[j]>=mod) {
                        sums[j]-=mod;
                    }
                }
            }
        }

//        long finalSum = 0;
//        for (int i = 0; i < n; i++) {
//            finalSum+=sums[i];
//        }

        printStream.println(sums[0]);

    }



}
// Problem: 909_C. Python Indentation
// Time complexity: quadratic
import java.util.*;
import java.io.*;
public class C {
  
  static InputReader in = new InputReader(System.in);
  static PrintWriter out = new PrintWriter(System.out);
  
  public static void main(String[] args) {
    int n = in.nextInt();
    int[] sol = new int[n];
    sol[0] = 1;
    int mod = 1000000007;
    int maxind = 0;
    boolean f = true;
    for (int i = 0; i < n; i++) {
      if (!f) {
        //int accum = sol[0];
        for (int j = 1; j <= maxind; j++) {
          sol[j] += sol[j-1];
          sol[j] %= mod;
        }
        //out.println(Arrays.toString(sol));
      }
      if (in.next().equals("f")) {
        maxind++;
        f = true;
      }
      else {
        f = false;
      }
    }
    int ans = 0;
    for (int i = 0; i <= maxind; i++) {
      ans += sol[i];
      ans %= mod;
    }
    out.println(ans);
    finish();
  }
  
  public static void finish() {
    out.close();
    in.close();
    System.exit(0);
  }

  static class InputReader implements Iterator<String>, Closeable {
    // Fast input reader. Based on Kattio.java from open.kattis.com
    // but has method names to match Scanner

    private BufferedReader r;
    private String line;
    private StringTokenizer st;
    private String token;

    public InputReader(InputStream i) {
      r = new BufferedReader(new InputStreamReader(i));
    }

    public boolean hasNext() {
      return peekToken() != null;
    }

    public int nextInt() {
      return Integer.parseInt(nextToken());
    }

    public double nextDouble() {
      return Double.parseDouble(nextToken());
    }

    public long nextLong() {
      return Long.parseLong(nextToken());
    }

    public String next() {
      return nextToken();
    }
    
    public String nextLine() {
      try {
        line = r.readLine();
      } catch (IOException e) {
        line = null;
      }
      token = null;
      st = null;
      return line;
    }
    
    public void close() {
      try {
        r.close();
      } catch (IOException e) {
      }
    }

    private String peekToken() {
      if (token == null)
        try {
          while (st == null || !st.hasMoreTokens()) {
            line = r.readLine();
            if (line == null)
              return null;
            st = new StringTokenizer(line);
          }
          token = st.nextToken();
        } catch (IOException e) {
        }
      return token;
    }

    private String nextToken() {
      String ans = peekToken();
      token = null;
      return ans;
    }
    
  }

}
// Problem: 909_C. Python Indentation
// Time complexity: quadratic

import java.util.Scanner;

/*
 * To change this license header, choose License Headers in Project Properties.
 * To change this template file, choose Tools | Templates
 * and open the template in the editor.
 */
/**
 *
 * @author EndUser
 */
public class R455D2PC {

    public static void main(String[] args) {
        final int MAX = 5000;
        final int MODULO = 1000000007;

        Scanner in = new Scanner(System.in);
        int n = in.nextInt();
        in.nextLine();

        int pre = 0;
        int size = 0;

        int[] block = new int[MAX];
        for (int i = 0; i < n; i++) {
            String command = in.nextLine();
            if (command.startsWith("s")) {
                block[size++] = pre;
                pre = 0;
            } else {
                pre++;
            }
        }

        if (pre != 0) {
            System.out.println(0);
            return;
        }

        int[][] result = new int[2][MAX + 1];
        int currentMax = 0;
        int preIndex = 0;
        result[preIndex][0] = 1;
        for (int i = 1; i < size; i++) {
            int currentIndex = preIndex ^ 1;
            int j = block[i - 1];
            for (int k = currentMax; k >= 0; k--) {
                result[currentIndex][k + j] = (result[currentIndex][k + j + 1] + result[preIndex][k]) % MODULO;
            }
            for (int k = j - 1; k >= 0; k--) {
                result[currentIndex][k] = result[currentIndex][j];

            }
            currentMax += j;
            preIndex = currentIndex;
//            for (int k = 0; k <= currentMax; k++) {
//                System.out.print(result[preIndex][k] + " ");
//                
//            }
//            System.out.println("");
        }

        int sum = 0;
        for (int i = 0; i <= currentMax; i++) {
            sum = (sum + result[preIndex][i]) % MODULO;
        }
        
        System.out.println(sum);
    }
}
// Problem: 909_C. Python Indentation
// Time complexity: quadratic
import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.io.PrintWriter;
import java.util.Arrays;
import java.util.StringTokenizer;

public class C {
	static int [][] memo;
	static int n;
	static char [] c;
	static int mod = (int)1e9+7;
	static int dp(int ind, int loops){
		if(ind == n)
			return loops == 0?1:0;
		if(memo[ind][loops] != -1)
			return memo[ind][loops];
		long ans = 0;
		if(c[ind] == 's'){
			ans = (ans + dp(ind+1, loops))%mod;
			if(loops > 0)
				ans = (ans + dp(ind, loops-1))%mod;
		}
		else{
			ans = (ans + dp(ind+1, loops+1))%mod;
		}
		return memo[ind][loops] = (int) ans;
	}
	public static void main(String[] args) throws IOException {
		Scanner sc = new Scanner(System.in);
		PrintWriter out = new PrintWriter(System.out);
		n = sc.nextInt();
		memo = new int[n+1][n+1];
		for(int [] i:memo)
			Arrays.fill(i, -1);
		c = new char[n];
		for (int i = 0; i < c.length; i++) {
			c[i] = sc.next().charAt(0);
		}
		out.println(dp(0,0));
		out.flush();
		out.close();
	}

	static class Scanner {
		BufferedReader bf;
		StringTokenizer st;

		public Scanner(InputStream i) {
			bf = new BufferedReader(new InputStreamReader(i));

		}

		public String next() throws IOException {
			while (st == null || !st.hasMoreTokens())
				st = new StringTokenizer(bf.readLine());
			return st.nextToken();
		}

		public int nextInt() throws NumberFormatException, IOException {
			return Integer.parseInt(next());
		}

		public double nextDouble() throws IOException {
			String x = next();
			StringBuilder sb = new StringBuilder("0");
			double res = 0, f = 1;
			boolean dec = false, neg = false;
			int start = 0;
			if (x.charAt(0) == '-') {
				neg = true;
				start++;
			}
			for (int i = start; i < x.length(); i++)
				if (x.charAt(i) == '.') {
					res = Long.parseLong(sb.toString());
					sb = new StringBuilder("0");
					dec = true;
				} else {
					sb.append(x.charAt(i));
					if (dec)
						f *= 10;
				}
			res += Long.parseLong(sb.toString()) / f;
			return res * (neg ? -1 : 1);
		}

		public long nextLong() throws NumberFormatException, IOException {
			return Long.parseLong(next());
		}
	}
}
// Problem: 909_C. Python Indentation
// Time complexity: quadratic
import java.io.*;
import java.util.*;
import java.math.*;
import java.util.concurrent.*;

public final class py_indent
{
    static BufferedReader br=new BufferedReader(new InputStreamReader(System.in));
	static FastScanner sc=new FastScanner(br);
    static PrintWriter out=new PrintWriter(System.out);
	static Random rnd=new Random();
	static int maxn=(int)(5e3+5);
	static long mod=(long)(1e9+7);
	
	static int add(long a,long b)
	{
		long ret=(a+b);
		
		if(ret>=mod)
		{
			ret%=mod;
		}
		
		return (int)ret;
	}
	
    public static void main(String args[]) throws Exception
    {
		int n=sc.nextInt();char[] a=new char[n+1];a[0]='s';
		
		for(int i=1;i<=n;i++)
		{
			a[i]=sc.next().charAt(0);
		}
		
		int[][] dp=new int[n+1][maxn],sum=new int[n+1][maxn];dp[0][0]=1;
		
		sum[0][0]=1;
		
		for(int i=1;i<maxn;i++)
		{
			sum[0][i]=add(sum[0][i],sum[0][i-1]);
		}
		
		for(int i=1;i<=n;i++)
		{
			if(a[i]=='f')
			{
				continue;
			}
			
			int curr=0,idx=0;
			
			for(int j=i-1;j>=0;j--)
			{
				if(a[j]=='s')
				{
					idx=j;break;
				}
				
				else
				{
					curr++;
				}
			}
			
			for(int j=0;j<maxn;j++)
			{
				int up=Math.max(0,j-curr);
					
				long now=(sum[idx][maxn-1]-(up==0?0:sum[idx][up-1]));
							  
				now=add(now,mod);
					
				dp[i][j]=add(dp[i][j],now);
			}
			
			sum[i][0]=dp[i][0];
			
			for(int j=1;j<maxn;j++)
			{
				sum[i][j]=add(dp[i][j],sum[i][j-1]);
			}
		}
		
		//out.println(dp[2][0]+" "+dp[2][1]+" "+dp[2][2]);
		
		out.println(dp[n][0]);out.close();
    }
}
class FastScanner
{
    BufferedReader in;
    StringTokenizer st;

    public FastScanner(BufferedReader in) {
        this.in = in;
    }
	
    public String nextToken() throws Exception {
        while (st == null || !st.hasMoreTokens()) {
            st = new StringTokenizer(in.readLine());
        }
        return st.nextToken();
    }
	
	public String next() throws Exception {
		return nextToken().toString();
	}
	
    public int nextInt() throws Exception {
        return Integer.parseInt(nextToken());
    }

    public long nextLong() throws Exception {
        return Long.parseLong(nextToken());
    }

    public double nextDouble() throws Exception {
        return Double.parseDouble(nextToken());
    }
}
// Problem: 909_C. Python Indentation
// Time complexity: quadratic
import java.io.BufferedReader;
import java.io.Closeable;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.util.Arrays;
import java.util.StringTokenizer;

public class C {
	
	public static void main(String[] args){
		try(Scanner sc = new Scanner(System.in)){
			final int N = sc.nextInt();
			
			String[] ins = new String[N];
			for(int i = 0; i < N; i++){
				ins[i] = sc.next();
			}
			
			final long MOD = 1000000007;
			long[] DP = new long[N];
			long[] nextDP = new long[N];
			
			DP[0] = 1;
			
			for(int i = 1; i < N; i++){
				Arrays.fill(nextDP, 0);
				if("f".equals(ins[i - 1])){
					for(int j = 0; j < N - 1; j++){
						nextDP[j + 1] += DP[j];
						nextDP[j + 1] %= MOD;
					}
				}else{
					for(int j = N - 1; j >= 0; j--){
						nextDP[j] += DP[j];
						nextDP[j] %= MOD;
						
						if(j < N - 1){
							nextDP[j] += nextDP[j + 1];
							nextDP[j] %= MOD;
						}
					}
				}
				
				{
					long[] tmp = DP;
					DP = nextDP;
					nextDP = tmp;
				}
			}
			
			long answer = 0;
			for(int i = 0; i < N; i++){
				answer += DP[i];
				answer %= MOD;
			}
			
			System.out.println(answer);
		}
	}

	public static class Scanner implements Closeable {
		private BufferedReader br;
		private StringTokenizer tok;

		public Scanner(InputStream is) {
			br = new BufferedReader(new InputStreamReader(is));
		}

		private void getLine() {
			try {
				while (!hasNext()) {
					tok = new StringTokenizer(br.readLine());
				}
			} catch (IOException e) { /* ignore */
			}
		}

		private boolean hasNext() {
			return tok != null && tok.hasMoreTokens();
		}

		public String next() {
			getLine();
			return tok.nextToken();
		}

		public int nextInt() {
			return Integer.parseInt(next());
		}
		
		public long nextLong() {
			return Long.parseLong(next());
		}

		public void close() {
			try {
				br.close();
			} catch (IOException e) { /* ignore */
			}
		}
	}
}
// Problem: 909_C. Python Indentation
// Time complexity: quadratic
import java.util.* ;
import java.io.* ;

public class PythonIndentation
{
	public static void main(String args[])
	{
		Scanner in = new Scanner(System.in) ;
		int n = in.nextInt() ;
		boolean[] lst = new boolean[n] ;
		for(int i=0;i<n;i++)
		{
			lst[i] = (in.next().equals("s"))?false:true ;
		}
		System.out.println(dp(lst)) ;
	}
	static void  arrayPrinter(int[][] dp)
	{
		System.out.println(":::") ;
		for(int i=0;i<dp.length;i++)
		{
			for(int j=0;j<dp[0].length;j++)
			{
				System.out.print(dp[i][j]+" ") ;
			}
			System.out.println() ;
		}
	}
	static int dp(boolean[] lst)
	{//false in lst means an "s" (simple statement), and true a "f"(for loop)
		int[][] dp = new int[2][lst.length] ;
		dp[0][0] = 1 ;
		for(int i=1;i<lst.length;i++)
		{
			// arrayPrinter(dp) ;
			for(int j=0;j<lst.length;j++)
			{
				if(lst[i-1])//(i-1)st statement is a for loop 
				{
					if(j==0)
						dp[i%2][j] = 0 ;
					else
						dp[i%2][j] = dp[(i-1)%2][j-1] ;
				}
			
				else//i-1 st statement is a simple statement
				{
					if(j==0)
					{
						int temp = 0 ;
						for(int k=0;k<lst.length;k++)
							temp = (temp+dp[(i-1)%2][k])%1000000007 ;
						dp[i%2][j] = temp ;
					}
					else
						dp[i%2][j] = (dp[i%2][j-1]-dp[(i-1)%2][j-1])%1000000007 ;
				}
			}
		}
		int ans = 0 ;
		for(int i=0;i<lst.length;i++)
		{
			ans = (ans + dp[(lst.length-1)%2][i])%1000000007 ;
		}
		if(ans<0)
			ans = ans + 1000000007 ;
		// arrayPrinter(dp) ;
		return ans ;
	}
}
// Problem: 909_C. Python Indentation
// Time complexity: quadratic
import java.util.Scanner;


public class Main {
	public static void main(String[] args){
		long MOD = 1000000007;
		Scanner sc = new Scanner(System.in);
		int n = sc.nextInt();
		long[][]dp = new long[n][5010];
		char[] program = new char[n];
		
		for(int i = 0; i < n; i++){
			program[i] = sc.next().charAt(0);
		}
		
		dp[0][0] = 1;
		
		long[] acc = new long[5010];
		
		acc[0] = 1;
		
		for(int i = 1 ; i < n; i++){
			for(int j = 0; j< 5010; j++){
				if(program[i-1] == 'f'){
					if(j - 1 >= 0){
						dp[i][j] = dp[i-1][j-1];
					}
				}else{
					dp[i][j] = acc[j];
				}
			}
			acc[5009] = dp[i][5009];
			for(int j = 5008; j >= 0; j--){
				acc[j] = (acc[j + 1] + dp[i][j]) % MOD;
			}
		}
		System.out.println(acc[0]);
	}
}