CodeChef submission 26787 (PYTH) plaintext list. Status: TLE, problem C4, contest MAY09. By shashikanth_a (Shashikanth ASV), 2009-05-09 03:09:36.
#!usr/bin/python
 
import string, sys, math 
 
def xcombinations(items, n):
	if n == 0:
		yield []
	else:
		for i in xrange(len(items)):
			#for cc in xcombinations(items[:i] + items[i+1:], n-1):
			for cc in xcombinations(items[i+1:], n-1):
				yield [items[i]] + cc
 
def hdp (L1,L2,prot_value):
	
	position_map={}
	repetations_map={}
	seq1=L1.split();
	sol_seq=[]
	protien_value={}
	for i in range(1,int(string.atoi(seq1[0]))+1,1):
		protien_value[chr(96+i)]=int(string.atoi(seq1[i]))	
 
	seq=[]
	sum=0
	count=0
	while 1:
		for i in range(count,len(L2),1):
#		if (sum+protien_value[L2[i]]) > prot_value:
#			continue
			if (sum+protien_value[L2[i]]) == prot_value:
				seq1=""
				for j in range(0,len(seq),1):
					seq1+=L2[seq[j]]
				seq1+=L2[i]
				sol_seq.append(seq1)
	
			if (sum+protien_value[L2[i]]) < prot_value:
				seq.append(i)
				sum+=protien_value[L2[i]]
	
			if i== ((len(L2))-1):
				#print '%s' % seq,i
				if len(seq)==0:
					break
				count=seq.pop()+1
				if count== ((len(L2))-1):
					if len(seq)==0:
						break
					count=seq.pop()+1
					sum-=protien_value[L2[count-1]]
				#print '%s 1 ' % seq,count,len(L2)
				sum-=protien_value[L2[count-1]]
 
		if len(seq)==0:
			break
#	print '%s' % L2[:2]
#	xcombinations(L2,len(L2))
#	print '%s' % sol_seq
#			print pm
#	for count in range(1,len(L2)+1,1):	
#		for pm in xcombinations(L2,count):
#			sum=0
#			for i in range (0,len(pm),1):
#				sum+=protien_value[pm[i]]
#				if sum==prot_value:
#					sol_seq.append(''.join(pm))
#	for count in range(0,len(L2),1):	
#		sum_par=0;
#		sum=protien_value.get(L2[count]);
#		seq=L2[count]
#		for count1 in range(count+1,len(L2),1):
#			print '%i' % sum,count,count1,seq
#			if ((sum)+ protien_value.get(L2[count1]))>prot_value:
#				continue;
#			if ((sum)+ protien_value.get(L2[count1]))==prot_value:
#				if (seq+(L2[count1])) in sol_seq:
#					1
#				else:
#					sol_seq.append(seq+(L2[count1]))
#				continue;
#			if ((sum)+ protien_value.get(L2[count1]))<prot_value:
#				seq+=(L2[count1])
#				sum+=protien_value.get(L2[count1])
#				continue;
#final_seq=sol_seq[0]		
	if len(sol_seq)==0:
		final_seq="IMPOSSIBLE"
	else:	
		sol_seq.sort()
		final_seq=sol_seq[0]
 
	return final_seq;
 
 
number_of_test_cases=sys.stdin.readline()
number_of_test_cases=string.strip(number_of_test_cases)
number_of_test_cases=int(string.atoi(number_of_test_cases))
 
input_array= []
sol_seq=[]
 
for i in range(0,3*(number_of_test_cases),1):
    input_array.insert(i,string.strip(sys.stdin.readline()));
 
 
 
for i in range(0,number_of_test_cases,1):
	L1=L2=""
	prot_value=0
	for j in range(0,3,1):
	    if j==0:
		L1=input_array[(3*i)+j];
	    if j==1:
		L2=input_array[(3*i)+j];
	    if j==2:
		prot_value=int(string.atoi(input_array[(3*i)+j]));
		
    	res=hdp(L1,L2,prot_value);
	print'%s'% res;