#include<bits/stdc++.h>

using namespace std;

#define pb push_back

#define ll long long

#define mem(a,b) memset(a,b,sizeof(a))

const int N=5e3+;

const int MOD=1e9+;

int dp[N][N];

char c[N];

int main()

{

    ios::sync_with_stdio(false);

    cin.tie();

    int n;

    cin>>n;

    for(int i=;i<=n;i++)cin>>c[i];

    for(int i=;i<n;i++)dp[n][i]=;

    for(int i=n-;i>=;i--)

    {

        int sum=;

        for(int j=;j<n;j++)

        {

            sum=(sum+dp[i+][j])%MOD;

            if(c[i]=='f')dp[i][j]=(dp[i][j]+dp[i+][j+])%MOD;

            else dp[i][j]=(dp[i][j]+sum)%MOD;

        }

    }

    cout<<dp[][]<<endl;

    return ;

}