# Original solution
#!/usr/bin/env python3
# vim: set fileencoding=utf-8

# pylint: disable=unused-import, invalid-name, missing-docstring, bad-continuation


"""Module docstring
"""

import sys

EMPTY = (0, 0, frozenset())


def solve(values, _nb, max_capacity):
    dp = [0] * (max_capacity + 1)
    for w, v in values:
        for j in range(max_capacity, w - 1, -1):
            if dp[j] < dp[j - w] + v:
                dp[j] = dp[j - w] + v
    return dp[max_capacity]


def solve_better(values, _nb, max_capacity):
    dp = [0] * (max_capacity + 1)
    for w, v in values:
        # dp = dp[:w] + [max(dp[j], dp[j - w] + v) for j in range(w, max_capacity + 1)]
        dp[w:] = [max(dpj, dpjw + v) for dpj, dpjw in zip(dp[w:], dp[:-w])]
    return dp[max_capacity]


def solve_slow(values, nb, max_capacity):
    dp = [[0 for _ in range(max_capacity + 1)] for _ in range(nb + 1)]
    for i in range(1, nb + 1):
        w, v = values[i - 1]
        for j in range(1, max_capacity + 1):
            if w <= j:
                dp[i][j] = max(dp[i - 1][j], dp[i - 1][j - w] + v)
            else:
                dp[i][j] = dp[i - 1][j]
    # print("\n".join(map(str, dp)))
    return dp[nb][max_capacity]


def do_job():
    "Do the work"
    # first line is number of test cases
    N, W = list(map(int, input().split()))
    values = []
    for _ in range(N):
        values.append(list(map(int, input().split())))
    result = solve(values, N, W)
    print(result)


def print_output(testcase, result) -> None:
    "Formats and print result"
    if result is None:
        result = "IMPOSSIBLE"
    print(("Case #{}: {}".format(testcase + 1, result)))


def main(argv=None):
    "Program wrapper."
    if argv is None:
        argv = sys.argv[1:]
    do_job()
    return 0


if __name__ == "__main__":
    import doctest

    doctest.testmod()
    sys.exit(main())


# Optimized solution
#!/usr/bin/env python3
# vim: set fileencoding=utf-8

# pylint: disable=unused-import, invalid-name, missing-docstring, bad-continuation


"""Module docstring
"""

import sys

EMPTY = (0, 0, frozenset())


def solve(values, _nb, max_capacity):
    dp = [0] * (max_capacity + 1)
    for w, v in values:
        for j in range(max_capacity, w - 1, -1):
            tmp = dp[j - w] + v
            if dp[j] < tmp:
                dp[j] = tmp
    return dp[max_capacity]


def solve_better(values, _nb, max_capacity):
    dp = [0] * (max_capacity + 1)
    for w, v in values:
        # dp = dp[:w] + [max(dp[j], dp[j - w] + v) for j in range(w, max_capacity + 1)]
        dp[w:] = [max(dpj, dpjw + v) for dpj, dpjw in zip(dp[w:], dp[:-w])]
    return dp[max_capacity]


def solve_slow(values, nb, max_capacity):
    dp = [[0 for _ in range(max_capacity + 1)] for _ in range(nb + 1)]
    for i in range(1, nb + 1):
        w, v = values[i - 1]
        for j in range(1, max_capacity + 1):
            if w <= j:
                dp[i][j] = max(dp[i - 1][j], dp[i - 1][j - w] + v)
            else:
                dp[i][j] = dp[i - 1][j]
    # print("\n".join(map(str, dp)))
    return dp[nb][max_capacity]


def do_job():
    "Do the work"
    # first line is number of test cases
    N, W = list(map(int, input().split()))
    values = []
    for _ in range(N):
        values.append(list(map(int, input().split())))
    result = solve(values, N, W)
    print(result)


def print_output(testcase, result) -> None:
    "Formats and print result"
    if result is None:
        result = "IMPOSSIBLE"
    print(("Case #{}: {}".format(testcase + 1, result)))


def main(argv=None):
    "Program wrapper."
    if argv is None:
        argv = sys.argv[1:]
    do_job()
    return 0


if __name__ == "__main__":
    import doctest

    doctest.testmod()
    sys.exit(main())