from math import sqrt
def dis(a, b):
return sqrt((a[0] - b[0]) ** 2 + (a[1] - b[1]) ** 2)
n = int(input())
l = [[*map(int, input().split())]for i in range(n)]
d = []
for i in range(0, n):
d.append(dis(l[i], l[(i + 1) % n]))
print(sum(d) - max(d))