import sys
import io, os
input = io.BytesIO(os.read(0,os.fstat(0).st_size)).readline

def main():

    n, m = map(int, input().split())
    VW = []
    for i in range(n):
        v, w = map(int, input().split())
        VW.append((v, w))
    VW.sort(key=lambda x: -x[0])
    dp = [-1]*(m+1)
    dp[0] = 0
    ans = 0
    for v, w in VW:
        for i in reversed(range(m+1)):
            if dp[i] == -1:
                continue
            if i+w <= m:
                ans = max(ans, (dp[i]+v)*v)
                dp[i+w] = max(dp[i+w], dp[i]+v)
    print(ans)

if __name__ == '__main__':
    main()