num = int(input()) lis = [4, 9] matrix = [0]*(num+1) for i in range(1, len(matrix)): matrix[i] = 99999 for j in range(len(lis)): if i >= lis[j]: if matrix[i-lis[j]] != -1: matrix[i] = min( matrix[i-lis[j]] + 1, matrix[i] ) if matrix[i] == 99999: matrix[i] = -1 print(matrix[-1])