def solve(N, blocks):
    blocks.sort(key=lambda x: x[0] + x[1])

    INF = 10 ** 18
    dp = [INF] * (N + 1)
    dp[0] = 0
    for i, (w, s) in enumerate(blocks):
        new_dp = dp.copy()
        for n in range(N):
            if dp[n] <= s:
                new_dp[n + 1] = min(dp[n] + w, new_dp[n + 1])
        dp = new_dp
    for n in range(N, -1, -1):
        if dp[n] != INF:
            return n
    return 0


N = int(input())
blocks = list(tuple(map(int, input().split())) for _ in range(N))
print(solve(N, blocks))