We have a sequence A of N non-negative integers.
Compute the sum of \prod _{i = 1} ^N \dbinom{B_i}{A_i} over all sequences B of N non-negative integers whose sum is at most M, and print it modulo (10^9 + 7).
Here, \dbinom{B_i}{A_i}, the binomial coefficient, denotes the number of ways to choose A_i objects from B_i objects, and is 0 when B_i < A_i.

-----Constraints-----
 - All values in input are integers.
 - 1 \leq N \leq 2000
 - 1 \leq M \leq 10^9
 - 0 \leq A_i \leq 2000

-----Input-----
Input is given from Standard Input in the following format:
N M
A_1 A_2 \ldots A_N

-----Output-----
Print the sum of \prod _{i = 1} ^N \dbinom{B_i}{A_i}, modulo (10^9 + 7).

-----Sample Input-----
3 5
1 2 1

-----Sample Output-----
8

There are four sequences B such that \prod _{i = 1} ^N \dbinom{B_i}{A_i} is at least 1:
 - B = \{1, 2, 1\}, where \prod _{i = 1} ^N \dbinom{B_i}{A_i} = \dbinom{1}{1} \times \dbinom{2}{2} \times \dbinom{1}{1} = 1;
 - B = \{2, 2, 1\}, where \prod _{i = 1} ^N \dbinom{B_i}{A_i} = \dbinom{2}{1} \times \dbinom{2}{2} \times \dbinom{1}{1} = 2;
 - B = \{1, 3, 1\}, where \prod _{i = 1} ^N \dbinom{B_i}{A_i} = \dbinom{1}{1} \times \dbinom{3}{2} \times \dbinom{1}{1} = 3;
 - B = \{1, 2, 2\}, where \prod _{i = 1} ^N \dbinom{B_i}{A_i} = \dbinom{1}{1} \times \dbinom{2}{2} \times \dbinom{2}{1} = 2.
The sum of these is 1 + 2 + 3 + 2 = 8.

```python

USER_FILENAME = "<user_code>"
import sys, json, builtins
import math, heapq, bisect, itertools, functools, collections, statistics, fractions, decimal, operator, array, random, re, string, os, pathlib
try:
    import resource as _res
except Exception:
    _res = None
from collections import Counter, defaultdict, deque, OrderedDict
from functools import lru_cache, reduce
from itertools import accumulate, permutations, combinations, product
from math import gcd, ceil, floor, sqrt
from decimal import Decimal
try:
    from typing import *
except Exception:
    pass
try:
    sys.setrecursionlimit(1_000_000)
except Exception:
    pass
try:
    import site as _site
    try:
        _sys_sites = _site.getsitepackages() if hasattr(_site, "getsitepackages") else []
        for _p in _sys_sites:
            if _p and _p not in sys.path:
                sys.path.append(_p)
    except Exception:
        pass
    try:
        _usp = _site.getusersitepackages()
        if isinstance(_usp, str):
            _usp = [_usp]
        for _p in _usp:
            if _p and _p not in sys.path:
                sys.path.append(_p)
    except Exception:
        pass
except Exception:
    pass

ns = {"__name__": "__main__"}
for _k, _v in list(globals().items()):
    if not _k.startswith("_"):
        ns[_k] = _v
_CODE = "from numba import njit\nN, M, *A = [int(_) for _ in open(0).read().split()]\nmod = 10**9 + 7\nsuma = sum(A)\nx = M + N\ny = N + suma\na = 1\nb = 1\n\n\n@njit('i8(i8,i8,i8)')\ndef pow_mod(base, exp, mod):\n    exp %= mod - 1\n    res = 1\n    while exp:\n        if exp & 1:\n            res = res * base % mod\n        base = base * base % mod\n        exp >>= 1\n    return res\n\n\n@njit('i8(i8,i8)')\ndef comb(x, y):\n    a = b = 1\n    for _ in range(y):\n        a *= x\n        b *= y\n        a %= mod\n        b %= mod\n        x -= 1\n        y -= 1\n    ret = a * pow_mod(b, mod - 2, mod) % mod\n    return ret\n\n\nprint((comb(M + N, N + suma)))\n"
_co = compile(_CODE, USER_FILENAME, "exec")
exec(_co, ns, ns)

```

Measured memory_bytes: