n = int(input())
H = []
W = []
for i in range(n):
H.append( list( map(int, input().split()) ) )
for i in range(n):
W.append( list( map(int, input().split()) ) )
totalTime = 0
def calculateTime(T1, T2):
if T1[0] <= T2[0] and T1[1] >= T2[0] and T1[1] <=T2[1]:
return T1[1] - T2[0]
elif T1[0] >= T2[0] and T2[1] >= T1[0] and T2[1] <= T1[1]:
return T2[1] - T1[0]
elif T1[0] <= T2[0] and T1[1] >= T2[1]:
return T2[1] - T2[0]
elif T1[0] >= T2[0] and T1[1] <= T2[1]:
return T1[1] - T1[0]
else:
return 0
i = 0
j = 0
while True:
time = calculateTime(H[i], W[j])
totalTime += time
if H[i][1] < W[j][1]:
i += 1
else:
j += 1
if i>=n or j>=n:
break
print(totalTime)
网友评论