def gcd(a,b):
    if b>a:
        a,b = b,a
    while b:
        a,b = b,a%b
    return a
t = int(input())
for i in range(t):
    k,n = map(int,input().split())
    arr = [int(x) for x in input().split()]
    ops = 0
    n1 = arr[0]
    n2 = arr[1]
    g = gcd(n1,n2)
    if g!=k:
        i,j = n1%k,n2%k
        if i and j:
            ops = min(i,k-i)+min(j,k-j)
        else:
            if i:
                ops = min(k-i,i)
            elif j:
                 ops = min(k-j,j)
    for i in range(2,n):
        g = gcd(k,arr[i])
        if g!=k:
            j = arr[i]%k
            ops += min(k-j,j)
    print(ops)

t = int(input())
for i in range(t):
    k,n = map(int,input().split())
    arr = [int(x) for x in input().split()]
    ops = 0

    for num in arr:
        rem = num%k
        if rem>0:
            ops+=min(rem,k-rem)
    print(ops)