#yuki1858
n,m=map(int,input().split())
l=[]
for i in range(n):
 l.append(list(map(int,input().split())))
l.sort(key=lambda x:x[0],reverse=True)
res=0
dp=[0]*(m+1)
for v,w in l:
 for i in range(m-w,-1,-1):
  dp[i+w]=max(dp[i+w],dp[i]+v)
 res=max(res,v*dp[m])
print(res)