#!/usr/bin/ python3.8
import sys
read = sys.stdin.buffer.read
readline = sys.stdin.buffer.readline
readlines = sys.stdin.buffer.readlines

N = int(readline())
m = map(int, read().split())

A, B = zip(*zip(m, m))
A = (0,) + A
B = (0,) + B + (0,)

INF = 10 ** 18
dp = [-INF] * (N + 1)  # その商品を最後に手数料対象とするときの、最適な節約額
dp1 = [-INF] * (N + 1)
dp1[0] = B[1]
for i in range(1, N + 1):
    dp[i] = dp1[i - 1] - A[i]
    if dp[i - 1] > dp[i]:
        dp[i] = dp[i - 1]
    dp1[i] = max(dp1[i - 1], dp[i] + B[i + 1])

save = max(dp[1:])
answer = sum(A) + sum(B) - save
print(answer)