import java.io.*; import java.util.*; import java.math.*; // import java.awt.Point; public class Main { InputStream is; PrintWriter out; String INPUT = ""; long MOD = 1_000_000_007; int inf = Integer.MAX_VALUE; void solve(){ int n = ni(); int K = ni(); long[] a = new long[n]; for(int i = 0; i < n; i++){ a[i] = nl(); } // Arrays.sort(a); long[] dp = new long[50001]; dp[0] = 1; // for(int i = 1; i < n; i++){ // long[] ndp = new long[50001]; // for(int j = 0; j <= i*(i-1)/2; j++){ // for(int k = 0; k <= i; k++){ // ndp[j+k] += dp[j]%MOD; // ndp[j+k] %= MOD; // } // } // // for(int j = 0; j < 10; j++){ // // out.println(ndp[j]); // // } // dp = ndp; // } for(int i = 1; i < n; i++){ long[] ndp = new long[50001]; for(int j = 0; j <= 45000; j++){ ndp[j] += dp[j]%MOD; ndp[j] %= MOD; ndp[j+i+1] -= dp[j]%MOD; ndp[j+i+1] %= MOD; // for(int k = 0; k <= i; k++){ // ndp[j+k] += dp[j]%MOD; // ndp[j+k] %= MOD; // } } for(int j = 1; j <= 50000; j++){ ndp[j] += ndp[j-1]%MOD; ndp[j] %= MOD; } dp = ndp; } long ans = 0; for(int i = 0; i <= K; i++){ ans += dp[i]%MOD; ans %= MOD; } // long res = 0; // for(int i = 0; i <= K; i++){ // out.println(dp[i]); // res += dp[i]%MOD; // res %= MOD; // ans += res%MOD; // ans %=MOD; // } out.println(ans); } void run() throws Exception { is = INPUT.isEmpty() ? System.in : new ByteArrayInputStream(INPUT.getBytes()); out = new PrintWriter(System.out); long s = System.currentTimeMillis(); solve(); out.flush(); if(!INPUT.isEmpty())tr(System.currentTimeMillis()-s+"ms"); } public static void main(String[] args) throws Exception { new Main().run(); } private byte[] inbuf = new byte[1024]; private int lenbuf = 0, ptrbuf = 0; private int readByte() { if(lenbuf == -1)throw new InputMismatchException(); if(ptrbuf >= lenbuf){ ptrbuf = 0; try { lenbuf = is.read(inbuf); } catch (IOException e) { throw new InputMismatchException(); } if(lenbuf <= 0)return -1; } return inbuf[ptrbuf++]; } private boolean isSpaceChar(int c) { return !(c >= 33 && c <= 126); } private int skip() { int b; while((b = readByte()) != -1 && isSpaceChar(b)); return b; } private double nd() { return Double.parseDouble(ns()); } private char nc() { return (char)skip(); } private String ns() { int b = skip(); StringBuilder sb = new StringBuilder(); while(!(isSpaceChar(b) && b != ' ')){ sb.appendCodePoint(b); b = readByte(); } return sb.toString(); } private char[] ns(int n) { char[] buf = new char[n]; int b = skip(), p = 0; while(p < n && !(isSpaceChar(b))){ buf[p++] = (char)b; b = readByte(); } return n == p ? buf : Arrays.copyOf(buf, p); } private char[][] nm(int n, int m) { char[][] map = new char[n][]; for(int i = 0;i < n;i++)map[i] = ns(m); return map; } private int[] na(int n) { int[] a = new int[n]; for(int i = 0;i < n;i++)a[i] = ni(); return a; } private int ni() { int num = 0, b; boolean minus = false; while((b = readByte()) != -1 && !((b >= '0' && b <= '9') || b == '-')); if(b == '-'){ minus = true; b = readByte(); } while(true){ if(b >= '0' && b <= '9'){ num = num * 10 + (b - '0'); }else{ return minus ? -num : num; } b = readByte(); } } private long nl() { long num = 0; int b; boolean minus = false; while((b = readByte()) != -1 && !((b >= '0' && b <= '9') || b == '-')); if(b == '-'){ minus = true; b = readByte(); } while(true){ if(b >= '0' && b <= '9'){ num = num * 10 + (b - '0'); }else{ return minus ? -num : num; } b = readByte(); } } private static void tr(Object... o) { System.out.println(Arrays.deepToString(o)); } }