# 1149 RGB 거리

# 틀린 코드 

n = int(input()) # 2<= n <= 1000 
cost = [0]*(n+1)
for i in range(1,n+1):
  cost[i] = list(map(int,input().split()))

# 집 마다 칠하는 비용이 다름! 
id = [0 for i in range(n+1)]
id[0] = cost[1].index(max(cost[1]))

total=0
for i in range(1,n+1):
  id[i] = cost[i].index(min(cost[i]))

  if (id[i]==id[i-1]) :
    id[i] = cost[i].index( min ( cost[i][ (id[i]+1)%3 ], cost[i][ (id[i]+2)%3 ]) )
 
  total += cost[i][ id[i] ]

print(total)

 

# 정답 

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

for i in range(1, len(p)):
    cost[i][0] = min(cost[i - 1][1], cost[i - 1][2]) + cost[i][0]
    cost[i][1] = min(cost[i - 1][0], cost[i - 1][2]) + cost[i][1]
    cost[i][2] = min(cost[i - 1][0], cost[i - 1][1]) + cost[i][2]
    
print(min(cost[n - 1][0], cost[n - 1][1], cost[n - 1][2]))