X = int(input())

# Each entry corresponds to j=0 to 6 (moves 1 to 7), storing the cumulative distance up to that move in a set
add_distance = [2, 4, 5, 6, 8, 9, 10]

candidates = []

for j in range(7):
    valid = False
    possible_k = 0
    
    if j in [0, 3, 6]:
        # Equation: X = 2k → k = X/2
        if X % 2 == 0:
            possible_k = X // 2
            valid = 1 <= possible_k <= 100
    elif j in [1, 4]:
        # Equation: X = 2k + 2 → k = (X-2)/2
        if (X - 2) >= 0 and (X - 2) % 2 == 0:
            possible_k = (X - 2) // 2
            valid = 1 <= possible_k <= 100
    elif j in [2, 5]:
        # Equation: X = 2k + 1 → k = (X-1)/2
        if X % 2 == 1:
            possible_k = (X - 1) // 2
            valid = 1 <= possible_k <= 100
    
    if valid:
        candidates.append((possible_k, j))

# Find the candidate with the smallest k, and then smallest j
if candidates:
    # Sort by k then j
    candidates.sort()
    best_k, best_j = candidates[0]
    total_distance = 10 * (best_k - 1) + add_distance[best_j]
    print(total_distance)
else:
    # According to the problem constraints, this path should never be taken
    print(0)