최종 제출 코드
my_list=[[0 for i in range(100)] for j in range(100)]
number = int(input())
count=0
for i in range(number):
a, b = map(int, input().split())
for j in range(a, a+10):
for k in range(b, b+10):
my_list[j][k] += 1
for i in range(100):
for j in range(100):
if my_list[i][j] > 0:
count += 1
print(count)