def solve(n, m, vw):
    ans = 0
    vw.sort(key = lambda x: x[0], reverse = True)
    dp = [[0] * (m + 1) for _ in range(n + 1)]
    for i in range(n):
        v, w = vw[i]
        for j in range(m + 1):
            dp[i + 1][j] = max(dp[i + 1][j], dp[i][j])
            if j + w <= m:
                if dp[i + 1][j + w] < dp[i][j] + v:
                    dp[i + 1][j + w] = dp[i][j] + v
                    ans = max(ans, v * dp[i + 1][j + w])
    return ans

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

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

print(solve(n, m, vw))