import sys

sys.setrecursionlimit(200005)
int1 = lambda x: int(x)-1
pDB = lambda *x: print(*x, end="\n", file=sys.stderr)
p2D = lambda x: print(*x, sep="\n", end="\n\n", file=sys.stderr)
def II(): return int(sys.stdin.readline())
def LI(): return list(map(int, sys.stdin.readline().split()))
def LLI(rows_number): return [LI() for _ in range(rows_number)]
def LI1(): return list(map(int1, sys.stdin.readline().split()))
def LLI1(rows_number): return [LI1() for _ in range(rows_number)]
def SI(): return sys.stdin.readline().rstrip()
dij = [(0, 1), (-1, 0), (0, -1), (1, 0)]
# dij = [(0, 1), (-1, 0), (0, -1), (1, 0), (1, 1), (1, -1), (-1, 1), (-1, -1)]
# inf = 18446744073709551615
inf = 4294967295
md = 10**9+7
# md = 998244353

n = II()
ll = []
to = []
indeg = [0]*n
for u in range(n):
    l, v = LI()
    v -= 1
    ll.append(l)
    to.append(v)
    indeg[v] += 1

def dfs(u):
    global ans
    ans += ll[u]
    fin[u] = 1
    v = to[u]
    if fin[v] == 1:
        if v == u: ans += ll[u]
        return v, ll[u]
    t, mn = dfs(v)
    mn = min(mn, ll[u])
    if t == u: ans += mn
    return t, mn

ans = 0
fin = [0]*n
for u in range(n):
    if indeg[u]: continue
    dfs(u)

for u in range(n):
    if fin[u]: continue
    dfs(u)

print(ans/2)