## https://yukicoder.me/problems/no/1858

def main():
    N, M = map(int, input().split())
    vw = []
    for _ in range(N):
        v, w = map(int, input().split())
        vw.append((v, w))
    
    vw.sort(key=lambda x : x[0], reverse=True)


    answer = 0
    dp = [-1] * (M + 1)
    dp[0] = 0
    for v, w in vw:
        # 答えを埋める
        for m in range(M + 1):
            if dp[m] != -1:
                if m + w <= M:
                    ans = dp[m] + v
                    ans *= v
                    answer = max(answer, ans)

        new_dp = dp.copy()
        for m in range(M + 1):
            if dp[m] != -1:
                if m + w <= M:
                    new_dp[m + w] = max(new_dp[m + w], dp[m] + v)
        dp = new_dp
    print(answer)


            

    


        




if __name__ == "__main__":
    main()