import sys from collections import defaultdict, Counter, deque from itertools import permutations, combinations, product, combinations_with_replacement, groupby, accumulate import operator from math import sqrt, gcd, factorial # from math import isqrt, prod,comb # python3.8用(notpypy) #from bisect import bisect_left,bisect_right #from functools import lru_cache,reduce #from heapq import heappush,heappop,heapify,heappushpop,heapreplace #import numpy as np #import networkx as nx #from networkx.utils import UnionFind #from numba import njit, b1, i1, i4, i8, f8 #from scipy.sparse import csr_matrix #from scipy.sparse.csgraph import shortest_path, floyd_warshall, dijkstra, bellman_ford, johnson, NegativeCycleError # numba例 @njit(i1(i4[:], i8[:, :]),cache=True) 引数i4配列、i8 2次元配列,戻り値i1 def input(): return sys.stdin.readline().rstrip() def divceil(n, k): return 1+(n-1)//k # n/kの切り上げを返す def yn(hantei, yes='Yes', no='No'): print(yes if hantei else no) #https://note.nkmk.me/python-union-find/から一部改変 class UnionFind(): def __init__(self, n): self.n = n self.parents = [-1] * n def find(self, x): if self.parents[x] < 0: return x else: self.parents[x] = self.find(self.parents[x]) return self.parents[x] def union(self, x, y): x = self.find(x) y = self.find(y) if x == y: return if self.parents[x] > self.parents[y]: x, y = y, x self.parents[x] += self.parents[y] self.parents[y] = x def size(self, x): return -self.parents[self.find(x)] def same(self, x, y): return self.find(x) == self.find(y) def members(self, x): root = self.find(x) return [i for i in range(self.n) if self.find(i) == root] def roots(self): return [i for i, x in enumerate(self.parents) if x < 0] def group_count(self): return len(self.roots()) def all_group_members(self): self.all_group_member=defaultdict(list) for i in range(self.n): self.all_group_member[self.find(i)].append(i) return self.all_group_member def __str__(self): return '\n'.join('{}: {}'.format(r, self.members(r)) for r in self.roots()) def main(): mod = 10**9+7 mod2 = 998244353 n,x=map(int, input().split()) S=list(map(int, input().split())) A=sum(x-ss for ss in S) print(x-A) if __name__ == '__main__': main()