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

VW.sort(key=lambda x: -x[0])
DP = [[-1 for _ in range(m + 1)] for _ in range(n + 1)]
DP[0][0] = 0
for i in range(n):
    v, w = VW[i]
    for j in range(m + 1):
        if DP[i][j] != -1:
            DP[i + 1][j] = max(DP[i + 1][j], DP[i][j])
            if j + w <= m:
                DP[i + 1][j + w] = max(DP[i + 1][j + w], DP[i][j + w], DP[i][j] + v)
ans = 0
for i in range(1, n + 1):
    maxv = max(DP[i])
    ans = max(ans, maxv * VW[i - 1][0])
print(ans)