def era(n):
    is_prime = [True]*(n+1)
    is_prime[0] = False
    is_prime[1] = False
    
    for i in range(2, int(n**0.5)+1):
        if not is_prime[i]:
            continue
        
        for j in range(2*i, n+1, i):
            is_prime[j] = False
    
    return [i for i in range(n+1) if is_prime[i]]
    
def bellman_ford():
    dist = [10**18]*(M+1)
    dist[M] = 0
    
    for i in range(M):
        for s, t, w in edges:
            if dist[s]!=10**18 and dist[t]>dist[s]+w:
                dist[t] = dist[s]+w
    
    return dist

M = int(input())
N = int(input())
C = list(map(int, input().split()))
edges = []

for i in range(M, -1, -1):
    for Ci in C:
        if i-Ci>=0:
            edges.append((i, i-Ci, -1))

dist = bellman_ford()
ans = 0

for pi in era(M-1):
    if dist[pi]==10**18:
        continue
    
    ans += -dist[pi]

minC = min(C)
ans += max(-dist[i] for i in range(minC) if dist[i]!=10**18)

print(ans)