N=int(input())
F=[]
for _ in range(N):
    w,s=map(int,input().split())
    F.append((w,s))

F.sort(key=lambda x:sum(x))

inf=float("inf")
DP=[inf]*(N+1)
DP[0]=0

for (w,s) in F:
    for k in range(N,0,-1):
        if DP[k-1]<=s:
            DP[k]=min(DP[k],DP[k-1]+w)

print(max([k for k in range(N+1) if DP[k]<inf]))