"""
name: Nicholas Tamassia

Honor Code and Acknowledgments:

        This work complies with the JMU Honor Code.

       Comments here on your code and submission.
"""

import pprint


def valid_shuffle(a: str, b: str, c: str) -> bool:

    memo: list[list[bool | None]] = [
        ([None] * (len(a) + 1)) for _ in range(0, len(b) + 1)
    ]

    memo[len(a)][len(b)] = True

    def recurse(i: int, j: int) -> bool:
        if i >= len(a) or j >= len(b):
            return False

        k: int = i + j
        if k == (len(c) - 2):
            return True

        a_val: bool | None = memo[i + 1][j]
        if a_val is None:
            a_val = recurse(i + 1, j) if a[i] == c[k] else False
            memo[i + 1][j] = a_val

        b_val: bool | None = memo[i][j + 1]
        if b_val is None:
            b_val = recurse(i, j + 1) if b[j] == c[k] else False
            memo[i][j + 1] = b_val

        memo[i][j] = a_val or b_val

        return a_val or b_val

    val = recurse(0, 0)

    pprint.pprint(memo)

    return val


# All modules for CS 412 must include a main method that allows it
# to imported and invoked from other python scripts
def main():
    a: str = input()
    b: str = input()
    c: str = input()

    print(valid_shuffle(a, b, c))


if __name__ == "__main__":
    main()