n = int(input())
ws = sorted((tuple(map(int, input().split())) for _ in range(n)), key=lambda p: sum(p))
dp = [0]
for w, s in ws:
    sz = len(dp)
    if dp[-1] <= s:
        dp.append(dp[-1] + w)
    for i in range(sz - 1)[::-1]:
        if dp[i] <= s:
            dp[i + 1] = min(dp[i + 1], dp[i] + w)
print(len(dp) - 1)