from sys import stdin

def 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()