W=int(input())
L=[tuple(map(int,input().split())) for i in range(W)]

DP=[[] for i in range(W+1)]
DP[0].append((0,0))

for i in range(W):
    DP[i].sort(reverse=True)
    lMAX=-1
    for m,l in DP[i]:
        if lMAX>l:
            continue
        else:
            lMAX=l
        

        DP[i+1].append((m+L[i][0],l))

        if i<W-1:
            DP[i+2].append((m-L[i+1][2],l+L[i+1][1]))

    #print(len(DP[i]))
    
ANS=-1<<30
for x,y in DP[W]:
    if x>=0 and y>ANS:
        ANS=y
        
print(ANS)