import sys
input = sys.stdin.readline

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


EDGE=[]
ANS=0

for i in range(N):
    x,y=PR[i]
    ANS+=x

    EDGE.append((x,0,i+1))
    if i>=1:
        EDGE.append((y,i,i+1))

# UnionFind

Group = [i for i in range(2*N+1)] # グループ分け
Nodes = [1]*(2*N+1) # 各グループのノードの数

def find(x):
    while Group[x] != x:
        x=Group[x]
    return x

def Union(x,y):
    if find(x) != find(y):
        if Nodes[find(x)] < Nodes[find(y)]:
            
            Nodes[find(y)] += Nodes[find(x)]
            Nodes[find(x)] = 0
            Group[find(x)] = find(y)
            
        else:
            Nodes[find(x)] += Nodes[find(y)]
            Nodes[find(y)] = 0
            Group[find(y)] = find(x)

EDGE.sort()

for w,x,y in EDGE:
    if find(x)==find(y):
        continue
    else:
        ANS+=w
        Union(x,y)

print(ANS)