def minimum_moves(n, instructions):
    # Define the four tiles
    tiles = ["up", "down", "right", "left"]
 
    # Initialize a dictionary to store the minimum moves required to each position
    dp = {tile: float("inf") for tile in tiles}
 
    # Start with any position (0 moves initially)
    for tile in tiles:
        dp[tile] = 0
 
    for instr in instructions:
        new_dp = {tile: float("inf") for tile in tiles}
        for current_tile in tiles:
            for target_tile in tiles:
                # If same tile, no movement needed; otherwise, 1 move
                cost = 0 if current_tile == target_tile else 1
                new_dp[target_tile] = min(new_dp[target_tile], dp[current_tile] + cost)
        dp = new_dp
 
    # Find the minimum moves among all final positions
    return min(dp.values())
 
# Input
n = int(input())
instructions = [input().strip() for _ in range(n)]
 
# Output
print(minimum_moves(n, instructions))

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Ngpkb3duCnJpZ2h0CmRvd24KdXAKcmlnaHQKZG93bg==

6
down
right
down
up
right
down