n = int(input())
AB = [list(map(int,input().split())) for i in range(n)]
sA,sB = 0,0
for a,b in AB:
    sA += a
    sB += b


ans = 0
for a,b in AB:
    sA -= a
    sB -= b
    ans += max(sA*b,sB*a)
print(ans)