Someone

element = {}
string = {}

string[0] = 'Li'
string[1] = 'Cs'
string[2] = 'H_'
string[3] = 'P-'
string[4] = 'CA'
string[5] = 'N_'
string[6] = 'H_'

element[0] = 'H_'
element[1] = 'He'
element[2] = 'Li'
element[3] = 'Be'
element[4] = 'B_'
element[5] = 'C_'
element[6] = 'N_'
element[7] = 'O_'
element[8] = 'F_'
element[9] = 'Ne'
element[10] = 'Na'
element[11] = 'Mg'
element[12] = 'Al'
element[13] = 'Si'
element[14] = 'P_'
element[15] = 'S_'
element[16] = 'Cl'
element[17] = 'Ar'
element[18] = 'K_'
element[19] = 'Ca'

ptval = {}
ptval[0] = '001'
ptval[1] = '002'
ptval[2] = '003'
ptval[3] = '004'
ptval[4] = '005'
ptval[5] = '006'
ptval[6] = '007'
ptval[7] = '008'
ptval[8] = '009'
ptval[9] = '010'
ptval[10] = '010'
ptval[11] = '011'
ptval[12] = '012'
ptval[13] = '013'
ptval[14] = '014'
ptval[15] = '015'
ptval[16] = '016'
ptval[17] = '017'
ptval[18] = '018'
ptval[19] = '019'



for i,v in element.iteritems():
        for j,w in string.iteritems():
		if v == w:		
			print ptval[v]
##			for k,x in ptval.iteritems():
##				v=ptval[x]	
##				print x