import sys
input = sys.stdin.readline

N, M = map(int, input().split())
T = [tuple(map(int, input().split())) for i in range(N)]
dp = [[0] * (M + 1) for i in range(N + 1)]
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)):
    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] + v)
      ans = max(ans, dp[i + 1][j + w] * v)

print(ans)