import sys
#sys.setrecursionlimit(n)
import heapq
import re
import bisect
import random
import math
import itertools
from collections import defaultdict, deque
from copy import deepcopy

n = int(input())
e = [[int(i) for i in input().split()] for i in range(n)]

mn = 0xFFFFFFFF
def prim(i):
  heap = []
  use = deque([False for _ in range(n)])
  heapq.heappush(heap, ((e[i][0] << 8) + i))
  ret = 0
  global mn
  while(heap):
    v = heapq.heappop(heap)
    c = (v >> 8) / 10
    p = v & 0xFF
    if ret >= mn:
      return 0xFFFFFFFF
    if not(use.count(False)):
      return ret
    if use[p]:
      continue
    nc = 0
    if use[e[p][1] - 1]:
      nc = e[p][0] / 2
    else:
      nc = e[p][0]
    use[p] = True
    ret += nc
    for j in range(n):
      nc = 0
      if use[e[j][1] - 1]:
        nc = e[j][0] / 2
      else:
        nc = e[j][0]
      heapq.heappush(heap, (int(nc * 10) << 8) + j)
  return 0xFFFFFFFF

for i in range(n):
  mn = min(mn, prim(i))
print(mn)