n = int(input())
ws = sorted((list(map(int,input().split())) for i in range(n)), key=sum)
INF = 1<<60
dp = [INF]*(n+2)
dp[0] = 0
for w,s in ws:
    for i in range(n)[::-1]:
        if dp[i] <= s: dp[i+1] = min(dp[i+1],dp[i]+w)
print(dp.index(INF)-1)