import sys
input=lambda:sys.stdin.readline().rstrip()

n=int(input())
t=[]
now=[0]*n
point=[]
limit=[]

for _ in range(n):
    t.append([*map(int,input().split())])
t=sorted(t)
for i in range(n-1,-1,-1):
    if now[i]!=0:
        now[t[i][0]]+=now[i]
        point.append(now[i])
        limit.append(t[i][1])
    else:
        now[t[i][0]]+=t[i][1]
limit.sort()
point.sort()
ans='YES'
if max(limit)>2200:
    ans='NO'
for x in range(len(limit)):
    if limit[x]<point[x]:
        ans='NO'
print(ans)