n,m = map(int,input().split())
A = list(map(int,input().split()))
B = list(map(int,input().split()))
lA = []
lB = []
for a in A:
    lA.append(0)
    for i in range(a):
        lA.append(1)

for b in B:
    lB.append(0)
    for i in range(b):
        lB.append(1)


dp = [[0]*(len(lB)+1) for i in range(len(lA)+1)]
for i in range(len(lA)+1):
    dp[i][0] = i

for i in range(len(lB)+1):
    dp[0][i] = i

for i in range(1,len(lA)+1):
    for j in range(1,len(lB)+1):
        if lA[i-1] == lB[j-1]:
            dp[i][j] = dp[i-1][j-1]
        else:
            dp[i][j] = min(dp[i-1][j-1]+1,dp[i][j-1]+1,dp[i-1][j]+1)

print(dp[-1][-1])