CodeForces B. Obtaining the String

http://codeforces.com/contest/1015/problem/B

 

You are given two strings $\mathrm{ss and tt.\; Both\; strings\; have\; length nn and\; consist\; of\; lowercase\; Latin\; letters.\; The\; characters\; in\; the\; strings\; are\; numbered\; from 11 to nn.}$

You can successively perform the following move any number of times (possibly, zero):

• swap any two adjacent (neighboring) characters of $\mathrm{ss (i.e.\; for\; any i=\{1,2,\dots ,n-1\}i=\{1,2,\dots ,n-1\} you\; can\; swap sisi and si+1)si+1).}$

You can't apply a move to the string $\mathrm{tt.\; The\; moves\; are\; applied\; to\; the\; string ss one\; after\; another.}$

Your task is to obtain the string $\mathrm{tt from\; the\; string ss.\; Find\; any\; way\; to\; do\; it\; with\; at\; most 104104 such\; moves.}$

You do not have to minimize the number of moves, just find any sequence of moves of length ${\mathrm{104104 or\; less\; to\; transform ss into tt.}}^{}$

Input

The first line of the input contains one integer $\mathrm{nn (1\le n\le 501\le n\le 50)\; —\; the\; length\; of\; strings ss and tt.}$

The second line of the input contains the string $\mathrm{ss consisting\; of nn lowercase\; Latin\; letters.}$

The third line of the input contains the string $\mathrm{tt consisting\; of nn lowercase\; Latin\; letters.}$

Output

If it is impossible to obtain the string $\mathrm{tt using\; moves,\; print\; "-1".}$

Otherwise in the first line print one integer $\mathrm{kk —\; the\; number\; of\; moves\; to\; transform ss to tt.\; Note\; that kk must\; be\; an\; integer\; number\; between 00and 104104 inclusive.}$

In the second line print $\mathrm{kk integers cjcj (1\le cj<n1\le cj<n),\; where cjcj means\; that\; on\; the jj-th\; move\; you\; swap\; characters scjscj and scj+1scj+1.}$

If you do not need to apply any moves, print a single integer $\mathrm{00 in\; the\; first\; line\; and\; either\; leave\; the\; second\; line\; empty\; or\; do\; not\; print\; it\; at\; all.}$

Examples

input

Copy

6
abcdef
abdfec

output

Copy

4
3 5 4 5 

input

Copy

4
abcd
accd

output

Copy

-1

代码：

#include <bits/stdc++.h>
using namespace std;

int N;
char A[55], B[55];
vector<int> T;
map<char, int> mp;

int main() {
    mp.clear();
    scanf("%d", &N);
    scanf("%s%s", A, B);
    for(int i = 0; i < N; i ++) {
        mp[A[i]] ++;
        mp[B[i]] --;
    }
    for(int i = 0; i < N; i ++) {
        if(mp[A[i]]) {
            printf("-1\n");
            return 0;
        }
    }
    for(int i = 0; i < N; i ++) {
        for(int j = i; j < N; j ++) {
            if(B[i] == A[j]) {
                for(int k = j; k > i; k --) {
                    swap(A[k], A[k - 1]);
                    T.push_back(k);
                }
                break;
            }
        }
    }

    printf("%d\n", T.size());
    for(int i = 0; i < T.size(); i ++) {
        printf("%s", i != 0 ? " " : "");
        printf("%d", T[i]);
    }
    printf("\n");
    return 0;
}