from math import gcd
import sys
input = sys.stdin.readline
n = int(input())
base = [*map(int,input().split())]
vectors = []
for _ in range(n-1):
x,y = map(int,input().split())
vectors.append([x-base[0],y-base[1]])
if vectors[-1][0] < 0:
vectors[-1] = [vectors[-1][0]*-1,vectors[-1][1]*-1]
def det(a,b):
return abs(a[0]*b[1]-a[1]*b[0])
mathgcd = gcd
def gcd(x,y):
if x*y == 0:
return 0
if x< 0 or y< 0:
return mathgcd(abs(x),abs(y))*-1
return mathgcd(x,y)
def reduce(a,b,c):
if det(a,b) == 0:
return (c,[gcd(a[0],b[0]),gcd(a[1],b[1])])
if det(a,c) == 0:
return (b,[gcd(a[0],c[0]),gcd(a[1],c[1])])
if det(b,c) == 0:
return (a,[gcd(b[0],c[0]),gcd(b[1],c[1])])
while det(b,c) != 0 and det(a,c) != 0 and det(a,b) != 0:
s = det(b,c)//det(a,b)
t = det(c,a)//det(a,b)
c[0] += s*a[0]+t*b[0]
c[1] += s*a[1]+t*b[1]
a,b,c = b,c,a
return reduce(a,b,c)
while len(vectors) > 2:
a,b,c = vectors.pop(),vectors.pop(),vectors.pop()
x,y = reduce(a,b,c)
vectors.append(x)
if vectors[-1][0] < 0:
vectors[-1] = [vectors[-1][0]*-1,vectors[-1][1]*-1]
vectors.append(y)
if vectors[-1][0] < 0:
vectors[-1] = [vectors[-1][0]*-1,vectors[-1][1]*-1]
if len(vectors) == 2:
a = abs(vectors[0][0]*vectors[1][1]-vectors[0][1]*vectors[1][0])
if a == 0:
print(-1)
else:
print(a)
elif len(vectors) < 2:
print(-1)
