n = int(input())
AB = [list(map(int, input().split())) for _ in range(n)]

accumA = [0 for _ in range(n)]
accumA[n - 1] = AB[n - 1][0]
accumB = [0 for _ in range(n)]
accumB[n - 1] = AB[n - 1][1]
for i in range(n - 2, -1, -1):
    accumA[i] = accumA[i + 1] + AB[i][0]
    accumB[i] = accumB[i + 1] + AB[i][1]
ans = 0
for i in range(n - 1):
    ans += max(AB[i][0] * accumB[i + 1], AB[i][1] * accumA[i + 1])
print(ans)