01 #include <iostream>

02 #include <queue>

03 using namespace std;

04

05 const int max1 = 2000000000;

06

07 class Map (

08 struct item {

09 string key; int value;

10} d[max1];

11int cnt;

12public:

13int find(string x) {

14for (int i = 0; i < cnt; ++i)

15if (d[i].key == x)

16return d[i].value;

17return -1;

18}

19static int end() { return -1; } 

20void insert(string k， int v) {

21d[cnt].key = k; d[cnt++].value = v; 

22}

23} s[2]；

24

25class Queue {

26string q[max1];

27int head, tail;

28public:

29void pop() { ++head; }

30string front() { return q[head + 1]; } 

31bool empty() { return head == tail; } 

32void push(string x) { q[++tail] = x; } 

33} q[2]；

34

35string st0，stl;

36int m;

37

38string LtoR(string s, int L, int R) { 

39string t = s;

40char tmp = t[L];

41for (int i = L; i < R; ++i)

42t[i] = t[i + 1];

43t[R] = tmp;

44return t;

45}

46

47string RtoL(string s， int L，int R) { 

48string t = s;

49char tmp = t[R];

50for (int i = R; i > L; --i)

51t[i] = t[i - 1]；

52t[L] = tmp;

53return t;

54}

55

56bool check(string st， int p，int step) { 

57if (s[p].find(st) != s[p].end()) 

58return false;

59++step;

60if (s[p ^ 1].find(st) == s[p].end()) { 

61s[p].insert(st, step); 

62q[p].push(st);

63return false;

64}

65cout << s[p ^ 1].find(st) + step << end1; 

66return true;

67}

68

69int main() {

70cin >> st0 >> stl;

71int len = st0.length()；

72if (len != stl.length()) { 

73cout << -1 << end1; 

74return 0；

75}

76if (st0 == st1) { 

77cout << 0 << end1; 

78return 0；

79}

80cin >> m;

81s[0].insert(st0, 0); s[1].insert(st1, 0); 

82q[0].push(st0); q[1].push(st1);

83for (int p = 0;

84!(q[0].empty() && q[1].empty());

85p ^=1) {

86string st - q[p].front(); q[p].pop();

87int step = s[p].find(st);

88if ((p == 0 &&

89(check(LtoR(st,m, len - 1), p, step) || 

90check(RtoL(st, 0, m), p, step)))

91|| 

92(p == 1 &&

93(check(LtoR(st,0, m), p, step) || 

94check(RtoL(st, m, len - 1), p, step)))) 

95return 0；

96}

97cout << -1 << end1; 

98return 0；

99}