from sys import stdindef merge(s1, s2): inf = float(1e3000) s = [] n1 = len(s1) n2 = len(s2) s1.append((inf,inf)) s2.append((inf,inf)) i = j = 0 a = s.append for k in xrange(0, n1+n2): (i1,x) = s1[i] (i2,y) = s2[j] if i1 < i2: a(s1[i]) i += 1 else: a(s2[j]) j += 1 return s def main(): sr = [] sra = sr.append for lj in stdin: s = [] sa = s.append ls = lj.split for p in ls(): (t, b) = p.split(',') t = int(t) sa( (t, b) ) sra(s) while len(sr) > 1: s = [] for i in xrange(0, len(sr), 2): if i + 1 == len(sr): s.append(sr[i]) else: s.append(merge(sr[i], sr[i+1])) sr = s print ''.join([b for (a,b) in sr[0]])main()