n = int(input())
ws = [list(map(int, input().split())) for _ in range(n)]

ws.sort(key=lambda x: x[0] + x[1])

dp = [1 << 60] * (n + 1)
dp[0] = 0

for w, s in ws:
    for i in range(n, 0, -1):
        if dp[i - 1] <= s:
            dp[i] = min(dp[i], dp[i - 1] + w)

for i in range(n, 0, -1):
    if dp[i] != 1 << 60:
        print(i)
        break