N, W = map(int, input().split())
vw = [list(map(int, input().split())) for _ in range(N)]

dp = [[0] * (W + 1) for _ in range(N + 1)]
for i in range(1, N + 1):
    for j in range(W + 1):
        if j >= vw[i-1][1]:
            dp[i][j] = max(dp[i-1][j], dp[i-1][j-vw[i-1][1]] + vw[i-1][0])
        else:
            dp[i][j] = dp[i-1][j]

if dp[N][W] == 0:
    print(-1)
else:
    print(dp[N][W])