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