#!/usr/bin/env python3
# from typing import *


# def solve(N: int, A: List[str], B: List[str]) -> str:
def solve(n, a, b):
    a.sort()
    b.sort()
    for i in range(n - 1):
        if a[i] != b[i]:
            return a[i]
    return a[n - 1]


# generated by oj-template v4.7.2 (https://github.com/online-judge-tools/template-generator)
def main():
    import sys
    tokens = iter(sys.stdin.read().split())
    N = int(next(tokens))
    A = [None for _ in range(N)]
    B = [None for _ in range(N - 1)]
    for i in range(N):
        A[i] = next(tokens)
    for i in range(N - 1):
        B[i] = next(tokens)
    assert next(tokens, None) is None
    a = solve(N, A, B)
    print(a)


if __name__ == '__main__':
    main()