def main():
    import sys
    from math import gcd
    input = sys.stdin.readline
    mod = 10 ** 9 + 7
    n = int(input())
    m = int(input())
    a = list(map(int, input().split()))
    b = list(map(int, input().split()))
    ans = 0
    for i in a:
        for j in b:
            ans += (i - 1) * (j + 1) + gcd(i, j) + 1
            ans %= mod
    print(ans)
if __name__ == "__main__":
    main()