with open('input.txt') as f:
    x = f.readlines()
    m = {}
    for s in x:
        p = s.strip().split(',')
        for i in p:
            if(i in m):
                m[i] += 1
            else:
                m[i] = 1
    mx = 0
    res = ''
    for i in m.items():
        if(mx < i[1]):
            mx = i[1]
            res = i[0]
    print(res)