# encoding=utf-8
import sys
line = sys.stdin.readline().strip("\n")
nums = map(int, line[1:len(line) - 1].split(","))
counter = {}
for n in nums:
if n in counter:
counter[n] += 1
else:
counter[n] = 1
res_count = 0
res_value = None
for k in counter.keys():
if res_count<counter.get(k):
res_count=counter.get(k)
res_value=k
print res_value