N = int(eval(input()))

p = tuple(map(int, input().split()))

a = list(p)

b = list(p)



c = 0

for i in range(N):

    if i+1 == a[i] and i == N-1:

        c += 1

    elif i+1 == a[i]:

        a[i], a[i+1] = a[i+1], a[i]

        c += 1

cc = 0        

for i in range(N)[::-1]:

    if i+1 == b[i] and i == 0:

        cc += 1

    if i+1 == b[i]:

        b[i], b[i-1] = b[i-1], b[i]

        cc += 1

        

print((min(c,cc)))
N = int(eval(input()))

p = tuple(map(int, input().split()))

a = list(p)

b = list(p)



c = 0

for i in range(N):

    if i+1 == a[i] and i == N-1:

        c += 1

    elif i+1 == a[i]:

        a[i], a[i+1] = a[i+1], a[i]

        c += 1

cc = 0        

for i in range(N)[::-1]:

    if i+1 == b[i] and i == 0:

        cc += 1

    elif i+1 == b[i]:

        b[i], b[i-1] = b[i-1], b[i]

        cc += 1

        

print((min(c,cc)))
N = int(eval(input()))
p = tuple(map(int, input().split()))
a = list(p)
b = list(p)
c = 0
for i in range(N):
    if i + 1 == a[i] and i == N - 1:
        c += 1
    elif i + 1 == a[i]:
        a[i], a[i + 1] = a[i + 1], a[i]
        c += 1
cc = 0
for i in range(N)[::-1]:
    if i + 1 == b[i] and i == 0:
        cc += 1
    if i + 1 == b[i]:
        b[i], b[i - 1] = b[i - 1], b[i]
        cc += 1
print((min(c, cc)))

N = int(eval(input()))
p = tuple(map(int, input().split()))
a = list(p)
b = list(p)
c = 0
for i in range(N):
    if i + 1 == a[i] and i == N - 1:
        c += 1
    elif i + 1 == a[i]:
        a[i], a[i + 1] = a[i + 1], a[i]
        c += 1
cc = 0
for i in range(N)[::-1]:
    if i + 1 == b[i] and i == 0:
        cc += 1
    elif i + 1 == b[i]:
        b[i], b[i - 1] = b[i - 1], b[i]
        cc += 1
print((min(c, cc)))

-    if i + 1 == b[i]: +    elif i + 1 == b[i]: