from math import sqrt
a = [int(x) for x in input().split()]
b = [int(x) for x in input().split()]
c = [int(x) for x in input().split()]
sab = [(a[0]+b[0])/2,(a[1]+b[1])/2]
sac = [(a[0]+c[0])/2,(a[1]+c[1])/2]
sbc = [(c[0]+b[0])/2,(c[1]+b[1])/2]
dabpul = sqrt((sab[0]-a[0])**2 + (sab[1]-a[1])**2)
dacpul = sqrt((sac[0]-a[0])**2 + (sac[1]-a[1])**2)
dbcpul = sqrt((sbc[0]-b[0])**2 + (sbc[1]-b[1])**2)
tc = sqrt((sab[0]-c[0])**2 + (sab[1]-c[1])**2)
tb = sqrt((sac[0]-b[0])**2 + (sac[1]-b[1])**2)
ta = sqrt((sbc[0]-a[0])**2 + (sbc[1]-a[1])**2)
print(min(abs(tc - dabpul),abs(tb - dacpul), abs(ta - dbcpul)))