#!/usr/bin/python
import os,sys,math
m = 105.65837
if len(sys.argv)!=2:
    print 'usage: make_initial_momentum_plots.py   file.dat'
    sys.exit(-1)
f = file(sys.argv[1],'r')
fl = f.readlines()
##for l in fl[:50]:
for l in fl:
    ls = l.split()
    if len(ls) == 9 and ls[1] == '1':
        KE = float(ls[2])/1E6
        p = math.sqrt( (KE+m)**2 - m**2 )
        print p