import sys

sys.setrecursionlimit(10**6)
int1 = lambda x: int(x)-1
p2D = lambda x: print(*x, sep="\n")
def II(): return int(sys.stdin.buffer.readline())
def FI(): return float(sys.stdin.buffer.readline())
def MI(): return map(int, sys.stdin.buffer.readline().split())
def MF(): return map(float, sys.stdin.buffer.readline().split())
def MI1(): return map(int1, sys.stdin.buffer.readline().split())
def LI(): return list(map(int, sys.stdin.buffer.readline().split()))
def LI1(): return list(map(int1, sys.stdin.buffer.readline().split()))
def LLI(rows_number): return [LI() for _ in range(rows_number)]
def LLI1(rows_number): return [LI1() for _ in range(rows_number)]
def BI(): return sys.stdin.buffer.readline().rstrip()
def SI(): return sys.stdin.buffer.readline().rstrip().decode()
dij = [(0, 1), (-1, 0), (0, -1), (1, 0)]
inf = 10**16
# md = 998244353
md = 10**9+7

from heapq import *

n=II()
to=[[] for _ in range(n+1)]
ans=0
for i in range(n):
    c,d=MI()
    ans+=c
    to[i].append((n,c))
    to[n].append((i,c))
    if i:
        to[i].append((i-1,d))
        to[i-1].append((i,d))

fin=[False]*(n+1)
fin[0]=True
hp=[]
for j,c in to[0]:
    heappush(hp,(c,j))
while hp:
    c,i=heappop(hp)
    if fin[i]:continue
    fin[i]=True
    ans+=c
    for j,c in to[i]:
        if fin[j]:continue
        heappush(hp,(c,j))

print(ans)