l,n = [int(input()) for _ in range(2)]
w = list(map(int, input().split()))
cntDic = {}
sw = []

for i in range(l):
    cntDic[str(i+1)] = 0

for we in w:
    cntDic[str(we)] += 1

for i in range(l):
    for _ in range(cntDic[str(i+1)]):
        sw.append(i+1)

cnt = 0
for i, swe in enumerate(sw):
    cnt += swe
    if cnt > l:
        print(i)
        exit()
print(len(w))