BOJ_1149.py

import sys
input = sys.stdin.readline

n = int(input())
dp = []
for _ in range(n):
    dp.append(list(map(int, input().split())))

for i in range(1, n):
    dp[i][0] += min(dp[i-1][1], dp[i-1][2])
    dp[i][1] += min(dp[i-1][0], dp[i-1][2])
    dp[i][2] += min(dp[i-1][0], dp[i-1][1])

print(min(dp[n-1]))