#!/usr/bin/env python3

n = int(input())
a, b = input(), input()

lookahead = 2

i = j = 0

while i < n and j < n:
    ok = False
    for k in range(lookahead + 1):
        if j + k < n and a[i] == b[j + k]:
            print(a[i], end="")
            i += 1
            j += k + 1
            ok = True
            break
        if i + k < n and a[i + k] == b[j]:
            print(b[j], end="")
            i += k + 1
            j += 1
            ok = True
            break
    if not ok:
        i += 1
        j += 1