import numpy as np

def solve(n, m, vw):
    ans = 0
    vw.sort(key = lambda x: x[0], reverse = True)
    dp = np.array([[int(0)] * (m + 1) for _ in range(n + 1)])
    for i in range(n):
        v, w = vw[i]
        if w > m: continue
        dp[i + 1][0:w] = dp[i][0:w]
        dp[i + 1][w:] = np.maximum(dp[i][w:], dp[i][0:m + 1 - w] + v)
        ans = max(ans, int(np.max(dp[i + 1])) * int(v))
    return ans

n, m = map(int,input().split())

vw = [list(map(int,input().split())) for _ in range(n)]

print(solve(n, m, vw))