def min_operations(N):
    dp = [float('inf')] * (N + 1)  # Initialize dp array with infinity
    dp[0] = 0  # Base case: zero operations needed for 0
    
    for i in range(2, N + 1):
        if i >= 2:
            dp[i] = min(dp[i], dp[i - 2] + 1)  # Subtract 2 operation
        if i >= 3:
            dp[i] = min(dp[i], dp[i - 3] + 1)  # Subtract 3 operation

    return dp[N] if dp[N] != float('inf') else -1  # Return -1 if no solution

# Example usage
N = int(input("Enter the integer N: "))
print("Minimum number of operations:", min_operations(N))