valid = []


def find(target, stack, depth=10, sequance=''):
    if stack == target:
        valid.append(sequance)
        return
    if depth <= 0:
        return
    t_stack = stack[:]
    t = stack[-1]
    del t_stack[-1]
    t_stack.insert(-2, t)
    find(target, t_stack, depth - 1, sequance + 't')
    s_stack = stack[:]
    t = stack[-1]
    del s_stack[-1]
    s_stack.insert(-1, t)
    find(target, s_stack, depth - 1, sequance + 's')
    d_stack = stack[:]
    d_stack.append(stack[-1])
    find(target, d_stack, depth - 1, sequance + 'd')


find(['c','b','a'][::-1], ['a', 'b', 'c'][::-1])
print(min(valid, key=len))