import sys

n = int(input())

# rgb = [list(map(int, sys.stdin.readline().split())) for _ in range(n)]

# if n==1:

# print(min(rgb[0]))

# else:

# for i in range(1,len(rgb)):

# for j in range(3):

# if j == 0:

# min_num = min(rgb[i-1][1],rgb[i-1][2])

# elif j == 1:

# min_num = min(rgb[i - 1][0], rgb[i - 1][2])

# else:

# min_num = min(rgb[i - 1][0], rgb[i - 1][1])

# rgb[i][j] += min_num

# print(min(rgb[n-1]))

dp = [list(map(int,sys.stdin.readline().split()))]

for i in range(1,n):

r, g, b = map(int,sys.stdin.readline().split())

nr = r + min(dp[i-1][1],dp[i-1][2])

ng = g + min(dp[i-1][0],dp[i-1][2])

nb = b + min(dp[i-1][1],dp[i-1][0])

dp.append([nr,ng,nb])

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