a = []
b = []
f = open('27_A.txt')
#f = open('tst.txt')
n = int(f.readline())
print(n)
for i in range(n):
    l = [int(i) for i in f.readline().split()]
    #print(type(l))
    a.append(l[0])
    b.append(l[1])
f.close()
print(a)
print(b)

mn = 10**40
for k in range(n):
    s = 0
    for i in range(n):
        s += abs(a[i] - a[k]) * b[i]
    mn = min(s,mn)
print(mn)