from collections import defaultdict

n = int(input())
row_dict = defaultdict(list)
col_dict = defaultdict(list)
for _ in range(n):
    a = list(map(int, input().split()))
    if a[0] == a[2]:
        col_dict[a[0]].append([min(a[1], a[3]), max(a[1], a[3])])
    else:
        row_dict[a[1]].append([min(a[0], a[2]), max(a[0], a[2])])

def merge(indexes):  # 合并区间基本模板
    indexes.sort(key=lambda x:x[0])
    res = []
    for index in indexes:
        if not res or res[-1][1] < index[0]:
            res.append(index)
        else:
            res[-1][1] = max(res[-1][1], index[1])
    return res

def bin_search(k, intervals):
        l, r = 0, len(intervals)-1
        while l < r:
            mid = (l+r+1)//2
            if intervals[mid][0] <= k:
                l = mid
            else:
                r = mid - 1
        return l

def is_cross(row, col, row_intervals, col_intervals):
    i = bin_search(row, col_intervals)  # 二分快速查找对对比区间
    j = bin_search(col, row_intervals)
    if col_intervals[i][1] >= row >= col_intervals[i][0] and row_intervals[j][1] >= col >= row_intervals[j][0]:
        return 1
    return 0

for row in row_dict:
    row_dict[row] = merge(row_dict[row])
for col in col_dict:
    col_dict[col] = merge(col_dict[col])

insert_num = 0
for row in row_dict:
    for col in col_dict:
        insert_num += is_cross(row, col, row_dict[row], col_dict[col])

total_num = 0
for row in row_dict:
    total_num += sum([i[1]-i[0]+1 for i in row_dict[row]])
for col in col_dict:
    total_num += sum([i[1]-i[0]+1 for i in col_dict[col]])

print(total_num-insert_num)