n,k = input().split()
C = list(map(int,input().split()))
n = int(n)

def search(x):
    C2 = C[:]
    for i in range(x-1):
        num = int(k[i])-1
        C2[num] -= 1
        if C2[num] < 0:
            return False
    num = int(k[x-1])
    for i in range(num,9):
        if C2[i]:
            return True
    return False

l = 0
r = n

while r > l + 1:
    m = (r+l)//2
    if search(m):
        l = m
    else:
        r = m
if l == 0:
    print(-1)
    exit()