def solution(n, lost, reserve):
answer = 0
students = [1 for i in range(n+2)]
for l in lost: students[l] -=1
for r in reserve: students[r] +=1
for i in range(1,n+1):
if students[i] == 0:
if students[i-1]==2:
students[i-1] = 1
students[i] = 1
elif students[i+1] == 2:
students[i] = 1
students[i+1] = 1
for i in range(1,n+1):
if students[i]:
answer+=1
return answer