import sys
read = sys.stdin.read
readline = sys.stdin.readline
readlines = sys.stdin.readlines

n = int(readline())
m = map(int, read().split())
p = sorted(zip(m, m), key=lambda x: sum(x))
S = 1
for x in p:
    T = S & (1<<x[1])-1
    S |= T << x[0]
print(S.bit_length() - 1)