import sys
import numpy as np


def main():
    n, x = map(int, input().split())
    S, A = np.fromstring(sys.stdin.read(), np.int64, sep=' ').reshape(-1, 2).T
    dp = np.zeros(x + 1, np.int64)
    for i in range(n):
        s, a = S[i], A[i]
        np.maximum(dp[s:], dp[:-s] + a, dp[s:])
    print(dp.max())



if __name__ == '__main__':
    main()