n = int(input())
list_t = []
list_p = []
price = 0
# ๊ฐ์ ์ ์ฅํด ๋์ ํ
์ด๋ธ ๋ฆฌ์คํธ ์์ฑ
dp_table = [0] * n+1
for i in range(n):
t, p = map(int, input().split())
list_t.append(t)
list_p.append(p)
for j in range(n-1,-1,-1):
# ์๋ด ๊ฐ๋ฅ ์๊ฐ
time = j + list_t[j]
# ์๋ด ๊ฐ๋ฅ ์๊ฐ์ด ํด์ฌ์ผ๋ณด๋ค ๊ธธ๋ค๋ฉด, ์๋ด ๋ถ๊ฐ๋ฅ
if time > n:
dp_table[j] = price
else:
dp_table[j] = max(list_p[j] + dp_table[j+list_t[j]], price)
price = dp_table[j]
print(price)