import sys
input = sys.stdin.readline

N, M = map(int, input().split())
T = [tuple(map(int, input().split())) for i in range(N)]
dp = [-1] * (M + 1)
dp[0] = 0
T.sort(reverse=True)
ans = 0
TW = 0
for i in range(N):
  v, w = T[i]
  TW += w
  for j in range(min(M, TW + 1), -1, -1):
    if dp[j] != -1 and j + w <= M:
      dp[j + w] = max(dp[j + w], dp[j] + v)
      ans = max(ans, dp[j + w] * v)

print(ans)