import sys

# sys.setrecursionlimit(200005)
int1 = lambda x: int(x)-1
p2D = lambda x: print(*x, sep="\n", end="\n\n")
def II(): return int(sys.stdin.readline())
def LI(): return list(map(int, sys.stdin.readline().split()))
def LLI(rows_number): return [LI() for _ in range(rows_number)]
def LI1(): return list(map(int1, sys.stdin.readline().split()))
def LLI1(rows_number): return [LI1() for _ in range(rows_number)]
def SI(): return sys.stdin.readline().rstrip()
# dij = [(0, 1), (-1, 0), (0, -1), (1, 0)]
# dij = [(0, 1), (-1, 0), (0, -1), (1, 0), (1, 1), (1, -1), (-1, 1), (-1, -1)]
inf = 18446744073709551615
# inf = 4294967295
md = 10**9+7
# md = 998244353

class UnionFind:
    def __init__(self, n):
        self.state = [-1]*n
        self.size_table = [1]*n
        # cntはグループ数
        self.cnt = n

    def root(self, u):
        stack = []
        while self.state[u] >= 0:
            stack.append(u)
            u = self.state[u]
        for v in stack: self.state[v] = u
        return u

    def same(self, u, v):
        return self.root(u) == self.root(v)

    def merge(self, u, v):
        u = self.root(u)
        v = self.root(v)
        if u == v: return False
        du = -self.state[u]
        dv = -self.state[v]
        if du < dv: u, v = v, u
        if du == dv: self.state[u] -= 1
        self.state[v] = u
        self.cnt -= 1
        self.size_table[u] += self.size_table[v]
        return True

    # グループの要素数
    def size(self, u):
        return self.size_table[self.root(u)]

n, m = LI()
aa = LI()
bb = LI()
ix = []

for i, a in enumerate(aa):
    ix.append((i, a))
for i, b in enumerate(bb):
    ix.append((i+n, b))

ix.sort(key=lambda x: x[1])
# print(ix)

dij = []
for k in range(len(ix)-1):
    i, x = ix[k]
    j, y = ix[k+1]
    if i < n and j < n: continue
    # if i > j: i, j = j, i
    dij.append((y-x, i, j))
dij.sort(key=lambda x: x[0])

uf = UnionFind(m+n+1)
t = m+n
for i in range(n): uf.merge(i, t)

ans = 0
for d, i, j in dij:
    if uf.same(i, t) and uf.same(j, t):
        continue
    uf.merge(i, j)
    ans += d

print(ans)