n = int(input())
A = [list(map(int, input().split())) for _ in range(n)]
asu = sum(a for a, b in A)
bsu = sum(b for a, b in A)
ans = 0
for a, b in A:
    if a * (bsu - b) >= b * (asu - a):
        asu -= a
        bsu -= b
        ans += a * bsu
    else:
        asu -= a
        bsu -= b
        ans += b * asu
print(ans)