L, N = map(int, input().split())
X = list(map(int, input().split()))

A = [X[0]]
for i in range(N-1):
    A.append(X[i+1]-X[i])
sumA = sum(A)

dp = [[False]*(sumA+1) for _ in range(len(A)+1)]
dp[0][0] = True
for i in range(len(A)):
    for j in range(sumA+1):
        if not dp[i][j]:
            continue
        if 1 <= i:
            dp[i+1][j] = True
        dp[i+1][j+A[i]] = True

ans = 10**18
for i in range(sumA+1):
    if dp[-1][i]:
        ans = min(ans, abs(i-(L-i)))

print(ans)