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


class Main {
    static final long MOD=1000000007;
    public static void main(String[] args) {
        MyScanner sc = new MyScanner();
        out = new PrintWriter(new BufferedOutputStream(System.out));
        int n=sc.nextInt();
        int k=sc.nextInt();
        int[]a=new int[n];
        for(int i=0;i<n;++i)a[i]=sc.nextInt();
        long[][]dp=new long[n+1][n*n];
        dp[0][0]=1;
        for(int i=0;i<n;++i){
            int u=i;
            int nxt=i+1;
            Arrays.fill(dp[nxt],0);
            for(int j=0;j<n*n;++j){
                if(j+i+1<n*n)
                    dp[nxt][j+i+1]=(dp[nxt][j+i+1]-dp[u][j]+MOD)%MOD;
                dp[nxt][j]=(dp[nxt][j]+dp[u][j])%MOD;
            }
            for(int j=1;j<n*n;++j)
                dp[nxt][j]=(dp[nxt][j]+dp[nxt][j-1])%MOD;
        }
        long ans=0;
        for(int i=0;i<=k;++i)
            ans=(ans+dp[n][i])%MOD;
        out.println(ans);
        out.close();
    }
    // http://codeforces.com/blog/entry/7018
    //-----------PrintWriter for faster output---------------------------------
    public static PrintWriter out;
    //-----------MyScanner class for faster input----------
    public static class MyScanner {
        BufferedReader br;
        StringTokenizer st;
        public MyScanner() {
            br = new BufferedReader(new InputStreamReader(System.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;
        }
    }
}