#!/usr/bin/env python

import sys, os
from math import *
import numpy as np
#import scipy as sp
from scipy import interpolate
from scipy.optimize import fmin

lines = open( 'LatticeConstants.dat' , 'r' ).readlines()
ListX=[]
ListY=[]
for LineNumber in range( len( lines )):
	ListX.append( float( lines[ LineNumber ].split()[0]) )
	ListY.append( float( lines[ LineNumber ].split()[1]) )

x = np.array( ListX )
y = np.array( ListY )

f = interpolate.UnivariateSpline(x, y)

print fmin(f, 3.5)