Takahashi has N days of summer vacation.
His teacher gave him M summer assignments. It will take A_i days for him to do the i-th assignment.
He cannot do multiple assignments on the same day, or hang out on a day he does an assignment.
What is the maximum number of days Takahashi can hang out during the vacation if he finishes all the assignments during this vacation?
If Takahashi cannot finish all the assignments during the vacation, print -1 instead.

-----Constraints-----
 - 1 \leq N \leq 10^6
 - 1 \leq M \leq 10^4
 - 1 \leq A_i \leq 10^4

-----Input-----
Input is given from Standard Input in the following format:
N M
A_1 ... A_M

-----Output-----
Print the maximum number of days Takahashi can hang out during the vacation, or -1.

-----Sample Input-----
41 2
5 6

-----Sample Output-----
30

For example, he can do the first assignment on the first 5 days, hang out on the next 30 days, and do the second assignment on the last 6 days of the vacation. In this way, he can safely spend 30 days hanging out.

Difficulty: EASY

Solutions:
(N, M) = map(int, input().split())
m = sum(list(map(int, input().split())))
if N - m >= 0:
	print(N - m)
else:
	print('-1')


(n, m) = map(int, input().split())
A = sum(list(map(int, input().split())))
print(max(n - A, -1))


(n, m) = map(int, input().split())
a = list(map(int, input().split()))
print(n - sum(a) if n - sum(a) >= 0 else -1)


(N, M, *A) = map(int, open(0).read().split())
print(max(N - sum(A), -1))


(N, M) = map(int, input().split())
lsA = list(map(int, input().split()))
sumA = sum(lsA)
print(max(-1, N - sumA))


(n, m) = map(int, input().split())
a = list(map(int, input().split()))
print(max(n - sum(a), -1))


(a, b) = map(int, input().split())
c = sum(map(int, input().split()))
print(max(a - c, -1))


(n, _, *a) = map(int, open(0).read().split())
print(max(-1, n - sum(a)))


(N, M) = map(int, input().split())
(*A,) = map(int, input().split())
a = sum(A)
ans = max(-1, N - a)
print(ans)


(n, m) = map(int, input().split())
ar = list(map(int, input().split()))
print(max(-1, n - sum(ar)))


(n, m) = map(int, input().split())
l = list(map(int, input().split()))
print(max(n - sum(l), -1))


(n, m) = map(int, input().split())
(*a,) = map(int, input().split())
ans = n - sum(a)
print([-1, ans][ans >= 0])


(n, m) = map(int, input().split(' '))
arr = list(map(int, input().split(' ')))
print(max(-1, n - sum(arr)))


(N, M) = map(int, input().split())
a = list(map(int, input().split()))
a_sum = sum(a)
print(max(N - a_sum, -1))


from numpy import cumsum
(n, m) = map(int, input().split())
l = list(map(int, input().split()))
l = cumsum(l)[-1]
if n < l:
	print('-1')
else:
	print(n - l)


(N, M) = map(int, input().split())
x = sum(map(int, input().split()))
print(N - x if N >= x else -1)


def __starting_point():
	(n, m) = map(int, input().split())
	A = list(map(int, input().split()))
	ans = n - sum(A)
	if ans >= 0:
		print(ans)
	else:
		print(-1)
__starting_point()


(N, M) = map(int, input().split())
A = list(map(int, input().split()))
sa = sum(A)
print(max(-1, N - sa))


(N, M) = map(int, input().split())
A_li = list(map(int, input().split()))
print(max(N - sum(A_li), -1))


(n, m) = map(int, input().split())
a = list(map(int, input().split()))
for i in a:
	n -= i
if n >= 0:
	print(n)
else:
	print('-1')


(n, m) = map(int, input().split())
for num in input().split():
	n -= int(num)
print(n if n >= 0 else -1)


(n, m) = map(int, input().split())
l = list(map(int, input().split()))
print('-1' if sum(l) > n else n - sum(l))


(n, m) = map(int, input().split())
asum = sum(map(int, input().split()))
print(-1 if n < asum else n - asum)


(N, M) = map(int, input().split())
A = map(int, input().split())
b = N - sum(A)
print(-1 if b < 0 else b)


(M, N) = map(int, input().split())
l = list(map(int, input().split()))
print(max(M - sum(l), -1))


(n, m) = tuple(map(int, input().split()))
x = list(map(int, input().split()))
for _ in x:
	n -= _
if n >= 0:
	print(n)
else:
	print(-1)


(n, m) = map(int, input().split(' '))
alist = list(map(int, input().split(' ')))
asum = sum(alist)
if n - asum >= 0:
	print(n - asum)
else:
	print(-1)


(N, M) = map(int, input().split())
A = list(map(int, input().split()))
print(N - sum(A) if sum(A) <= N else -1)


(n, m, *a) = map(int, open(0).read().split())
s = sum(a)
print(max(-1, n - s))


(n, m) = map(int, input().split())
days = input().split()
x = 0
for day in days:
	x = x + int(day)
if x <= n:
	print(n - x)
else:
	print(-1)


a = list(map(int, input().rstrip().split()))
b = list(map(int, input().rstrip().split()))
x = a[0] - sum(b)
if x < 0:
	print(-1)
else:
	print(x)


(n, m) = map(int, input().split())
aa = list(map(int, input().split()))
homework = sum(aa)
if n < homework:
	print(-1)
else:
	print(n - homework)


(n, m) = map(int, input().split())
s = sum(tuple(map(int, input().split())))
print(-1 if s > n else n - s)


(N, M) = list(map(int, input().split()))
A = list(map(int, input().split()))

def answer(N: int, M: int, A: list) -> int:
	A = sum(A)
	if N < A:
		return -1
	else:
		return N - A
print(answer(N, M, A))


n = int(input().split()[0])
print(max(-1, n - sum(map(int, input().split()))))


I = lambda : list(map(int, input().split()))
(n, m) = I()
n = n - sum(I())
print(n if n >= 0 else -1)


(N, M) = map(int, input().split())
A = [int(i) for i in input().split()]
print(max(-1, N - sum(A)))


(a, b) = map(int, input().split())
c = [int(x) for x in input().split()]
s = sum(c)
print(max(a - s, -1))


(d, n) = map(int, input().split())
a = list(map(int, input().split()))
print(max(-1, d - sum(a)))


radi = input()
list = radi.split(' ')
N = int(list[0])
days = input()
total = 0
a = days.split(' ')
for items in a:
	total += int(items)
if total > N:
	print(-1)
else:
	print(N - total)


(N, M) = map(int, input().split())
A = list(map(int, input().split()))
r = N - sum(A)
if r < 0:
	r = -1
print(r)


(n, t) = map(int, input().split())
s = n - sum(map(int, input().split()))
if s < 0:
	print(-1)
else:
	print(s)


(N, M) = map(int, input().split())
(*A,) = map(int, input().split())
print(max(-1, N - sum(A)))


(n, m) = map(int, input().split())
lst = list(map(int, input().split()))
print(max(-1, n - sum(lst)))


(n, m) = map(int, input().split())
A = list(map(int, input().split()))
t = sum(A)
print(n - t if t <= n else '-1')


(N, M) = map(int, input().split())
print(max(N - sum([int(x) for x in input().split()]), -1))


s = 0
(n, m) = map(int, input().split())
a = list(map(int, input().split()))
for i in range(0, len(a)):
	s = s + a[i]
if s > n:
	print(-1)
	return
print(n - s)


(N, M) = list(map(int, input().split()))
A_list = []
for i in range(1, M + 1):
	A_list.append('A_' + str(i))
A_list = list(map(int, input().split()))
answer = N - sum(A_list)
if answer >= 0:
	print(answer)
else:
	print(-1)


(N, M) = map(int, input().split())
work = list(map(int, input().split()))
if N >= sum(work):
	answer = N - sum(work)
else:
	answer = '-1'
print(answer)


(N, M) = map(int, input().split())
(*A,) = map(int, input().split())
for a in A:
	N -= a
print(-1 if N < 0 else N)


print(max(-1, list(map(int, input().split()))[0] - sum(map(int, input().split()))))


(N, _) = map(int, input().split())
s = sum(map(int, input().split()))
print(N - s if N >= s else -1)


(n, m) = map(int, input().split())
li = list(map(int, input().split()))
print(max(n - sum(li), -1))


import sys
(N, M) = map(int, input().split())
A = list(map(int, input().split()))
sum_day = sum(A)
ans = N - sum_day
if ans < 0:
	print(-1)
else:
	print(ans)


(n, m) = map(int, input().split())
s = sum(list(map(int, input().split())))
print(max(-1, n - s))


(n, m) = map(int, input().split())
a = map(int, input().split())
ans = max(-1, n - sum(a))
print(ans)


(n, m, *l) = [int(i) for i in open(0).read().split()]
print(max(-1, n - sum(l)))


(n, m) = map(int, input().split())
a_map = map(int, input().split())
print(max(-1, n - sum(a_map)))


def readinput():
	(n, m) = list(map(int, input().split()))
	a = list(map(int, input().split()))
	return (n, m, a)

def main(n, m, a):
	days = sum(a)
	if days > n:
		return -1
	else:
		return n - days

def __starting_point():
	(n, m, a) = readinput()
	ans = main(n, m, a)
	print(ans)
__starting_point()


(n, m) = map(int, input().split())
a = [int(i) for i in input().split()]
print(max(-1, n - sum(a)))


list = []
(n, m) = map(int, input().split())
a = input().split()[0:m]
for num in a:
	num = int(num)
	list.append(num)
answer = n - sum(list)
if n < sum(list):
	answer = -1
print(answer)


(n, m) = map(int, input().split())
aa = list(map(int, input().split()))
print(max(-1, n - sum(aa)))


(m, n, *aa) = map(int, open(0).read().split())
ans = m - sum(aa)
if ans < 0:
	print(-1)
else:
	print(ans)


R = lambda : map(int, input().split())
(n, m) = R()
print(max(n - sum(R()), -1))


(n, _) = map(int, input().split())
a = n - sum(map(int, input().split()))
print(-1 if a < 0 else a)


def i_input():
	return int(input())

def i_map():
	return list(map(int, input().split()))

def i_list():
	return list(map(int, input().split()))

def i_row(N):
	return [int(input()) for _ in range(N)]

def i_row_list(N):
	return [list(map(int, input().split())) for _ in range(N)]
(dnum, hwnum) = i_map()
hws = i_list()
if dnum >= sum(hws):
	ans = dnum - sum(hws)
	print(ans)
else:
	print(-1)


(n, m) = map(int, input().split())
sum_a = sum(map(int, input().split()))
print(max(n - sum_a, -1))


(n, m) = map(int, input().split())
works = map(int, input().split())
print(max(n - sum(works), -1))


(N, M, *A) = map(int, open(0).read().split())
play = N - sum(A)
print(play if play >= 0 else -1)


(n, m) = map(int, input().split())
A = list(map(int, input().split()))
day = 0
for i in range(len(A)):
	day = day + A[i - 1]
if n < day:
	print(-1)
else:
	ans = n - day
	print(ans)


def N():
	return int(input())

def L():
	return list(map(int, input().split()))

def NL(n):
	return [list(map(int, input().split())) for i in range(n)]
mod = pow(10, 9) + 7
import sys
import math
import collections
(n, m) = L()
a = L()
print(max(n - sum(a), -1))


def my_input():
	return list(map(int, input().split()))
(n, _) = my_input()
ans = n - sum(my_input())
print(ans if ans >= 0 else -1)


def i():
	return [int(x) for x in input().split()]
(n, m) = i()
c = sum(i())
print(n - c if n >= c else -1)


(a, _) = map(int, input().split())
li = [int(x) for x in input().split()]
s = sum(li)
print(max(a - s, -1))


(n, m, *a) = map(int, open(0).read().split())
a = sum(a)
print(n - a if n >= a else -1)


(n, m) = map(int, input().split())
a_list = list(map(int, input().split()))
a_total = sum(a_list)
ans = n - a_total
if ans < 0:
	print(-1)
else:
	print(ans)


(n, m) = tuple(map(int, input().split(' ')))
print(max(n - sum(map(int, input().split(' '))), -1))


(n, m) = map(int, input().split())
f = n - sum(map(int, input().split()))
print(-1 if f < 0 else f)


(n, m) = map(int, input().split())
arr = [int(x) for x in input().split()]
s = sum(arr)
print(max(-1, n - s))


(n, m, *A) = map(int, open(0).read().split())
print(max(n - sum(A), -1))


(a, b) = map(int, input().split())
c = list(map(int, input().split()))
d = sum(c)
print(a - d if a - d >= 0 else -1)


(a, b) = [int(i) for i in input().split()]
arr = [int(i) for i in input().split()]
print(max(a - sum(arr), -1))


(N, _) = input().split()
a = map(int, input().split())
d = int(N) - sum(a)
if d < 0:
	print(-1)
else:
	print(d)


(n, m) = map(int, input().split())
a = map(int, input().split())
d = n - sum(a)
if d < 0:
	d = -1
print(d)


(n, m) = map(int, input().split())
xdays = sum(list(map(int, input().split())))
print(max(-1, n - xdays))


l = [int(i) for i in input().split()]
m = [int(i) for i in input().split()]
print(max(-1, l[0] - sum(m)))


(N, M) = map(int, input().split())
t = N - sum((int(x) for x in input().split()))
print(-1 if t < 0 else t)


def main():
	(n, m) = list(map(int, input().split()))
	homeworks = tuple(map(int, input().split()))
	print(max(-1, n - sum(homeworks)))
	return

def __starting_point():
	main()
__starting_point()


(N, X) = map(int, input().split())
Y = N - sum(map(int, input().split()))
print(('-1', Y)[Y >= 0])


(N, M) = map(int, input().split())
As = list(map(int, input().split()))
print(max(N - sum(As), -1))


def inpl():
	return list(map(int, input().split()))
(N, M) = inpl()
print(max(-1, N - sum(inpl())))


(n, m) = map(int, input().split())
data = list(map(int, input().split()))
print(max(n - sum(data), -1))


(N, M) = map(int, input().split())
S = sum(map(int, input().split()))
print(max(-1, N - S))


(n, m) = map(int, input().split())
a = [int(s) for s in input().split()]
days = n - sum(a)
print(days) if days >= 0 else print(-1)


(N, M) = map(int, input().split())
ans = N - sum(list(map(int, input().split())))
print(max(ans, -1))


(n, m) = list(map(int, input().split()))
a = [int(x) for x in input().split()]
ans = n - sum(a)
print(str(max(ans, -1)))


(n, _) = map(int, input().split())
ans = n - sum(map(int, input().split()))
if ans < 0:
	ans = -1
print(ans)


(N, M) = list(map(int, input().split()))
num_list = list(map(int, input().split()))
x = N - sum(num_list)
if x >= 0:
	print(x)
else:
	print(-1)


(N, _) = map(int, input().split())
A = sum(map(int, input().split()))
print(N - A) if N >= A else print(-1)


(a, b) = list(map(int, input().split()))
s = sum(list(map(int, input().split())))
print(max(a - s, -1))


(n, m) = map(int, input().split())
t = list(map(int, input().split()))
print(max(-1, n - sum(t)))


(N, M) = map(int, input().split())
la = list(map(int, input().split()))
print(max(N - sum(la), -1))


(N, K) = [int(s) for s in input().split()]
ls = [int(s) for s in input().split()]
print(max([N - sum(ls), -1]))


def __starting_point():
	(N, M) = list(map(int, input().split()))
	li = list(map(int, input().split()))
	if N >= sum(li):
		print(N - sum(li))
	else:
		print('-1')
__starting_point()


(n, m) = map(int, input().split())
a = sum(map(int, input().split()))
print([n - a, -1][n < a])


import math, string, itertools, fractions, heapq, collections, re, array, bisect, sys, random, time, copy, bisect
import sys
sys.setrecursionlimit(10 ** 7)
inf = 10 ** 20
mod = 10 ** 9 + 7
stdin = sys.stdin
ni = lambda : int(ns())
nf = lambda : float(ns())
na = lambda : list(map(int, stdin.readline().split()))
nb = lambda : list(map(float, stdin.readline().split()))
ns = lambda : stdin.readline().rstrip()
(N, M) = na()
A = na()
print(max(N - sum(A), -1))


def calc(n, m):
	holidays = n
	a = list((int(v) for v in input().split()))
	ans = holidays - sum(a)
	return ans if ans >= 0 else -1

def main():
	(n, m) = list(map(int, input().split()))
	return calc(n, m)

def __starting_point():
	print(main())
__starting_point()


(n, m) = map(int, input().split())
tot = sum(map(int, input().split()))
print(max(-1, n - tot))


(a, b) = map(int, input().split())
li = list(map(int, input().split()))
sum = 0
for i in li:
	sum += i
if a > sum:
	print(a - sum)
elif a == sum:
	print(0)
else:
	print(-1)


(n, m) = map(int, input().split())
l = [int(i) for i in input().split()]
s = sum(l)
print(max(-1, n - s))


(n, m) = map(int, input().split())
a = [int(i) for i in input().split()]
print(n - sum(a) if n >= sum(a) else -1)