N,M = map(int,input().split())
l = []
for i in range(N):
    v,w = map(int,input().split())
    l.append((v,w))
l.sort(reverse = True,key = lambda s:s[0])
dp = [[0] * (M+1) for _ in range(N+1)]
ans = 0
for i in range(N):
    v,w = l[i]
    for j in range(M+1):
        if j + w <= M:
            tmp = (dp[i][j] + v) * v
            if tmp > ans:
                ans = tmp
    for j in range(M+1):
        dp[i+1][j] = max(dp[i+1][j],dp[i][j])
    for j in range(M+1):
        if j + w <= M:
            dp[i+1][j+w] = max(dp[i+1][j+w],dp[i][j] + v)
print(ans)