#ifdef LOCAL111
	#define _GLIBCXX_DEBUG
#else
	#define NDEBUG
#endif
#define _USE_MATH_DEFINES
#include <bits/stdc++.h>
const int INF = 1e9;
using namespace std;
template<typename T, typename U> ostream& operator<< (ostream& os, const pair<T,U>& p) { cout << '(' << p.first << ' ' << p.second << ')'; return os; }

#define endl '\n'
#define ALL(a)  (a).begin(),(a).end()
#define SZ(a) int((a).size())
#define FOR(i,a,b) for(int i=(a);i<(b);++i)
#define RFOR(i,a,b) for (int i=(b)-1;i>=(a);i--)
#define REP(i,n)  FOR(i,0,n)
#define RREP(i,n) for (int i=(n)-1;i>=0;i--)
#ifdef LOCAL111
	#define DEBUG(x) cout<<#x<<": "<<(x)<<endl
	template<typename T> void dpite(T a, T b){ for(T ite = a; ite != b; ite++) cout << (ite == a ? "" : " ") << *ite; cout << endl;}
#else
	#define DEBUG(x) true
	template<typename T> void dpite(T a, T b){ return; }
#endif
#define F first
#define S second
#define SNP string::npos
#define WRC(hoge) cout << "Case #" << (hoge)+1 << ": "
template<typename T> void pite(T a, T b){ for(T ite = a; ite != b; ite++) cout << (ite == a ? "" : " ") << *ite; cout << endl;}
template<typename T> bool chmax(T& a, T b){if(a < b){a = b; return true;} return false;}
template<typename T> bool chmin(T& a, T b){if(a > b){a = b; return true;} return false;}

typedef long long int LL;
typedef unsigned long long ULL;
typedef pair<int,int> P;

int editDist(string s, string t){
	using P = pair<int,int>;
	const int del_cost = 1, ins_cost = 1, rep_cost = 1;
	int n = s.size(), m = t.size();
	array<P,4> vec = {P{-1,0}, P{0,-1}, P{-1,-1}, P{-1,-1}};

	vector<vector<int>> dp(n+1,vector<int>(m+1,INF));
	vector<vector<int>> pre(n+1,vector<int>(m+1,-1));
	for(int i = 0; i < n+1; ++i) {
		pre[i][0] = 0;
		dp[i][0] = i*del_cost;
	}
	for(int i = 0; i < m+1; ++i) {
		pre[0][i] = 1;
		dp[0][i] = i*ins_cost;
	}
	for(int i = 0; i < n; ++i) {
		for(int j = 0; j < m; ++j) {
			if(s[i] == t[j]){
				if(dp[i+1][j+1] > dp[i][j]){
					dp[i+1][j+1] = dp[i][j];
					pre[i+1][j+1] = 3;
				}
			}else{
				if(dp[i+1][j+1] > dp[i][j]+rep_cost){
					dp[i+1][j+1] = dp[i][j]+rep_cost;
					pre[i+1][j+1] = 2;
				}
			}
			if(dp[i+1][j+1] > dp[i+1][j]+ins_cost){
				dp[i+1][j+1] = dp[i+1][j]+ins_cost;
				pre[i+1][j+1] = 1;
			}
			if(dp[i+1][j+1] > dp[i][j+1]+del_cost){
				dp[i+1][j+1] = dp[i][j+1]+del_cost;
				pre[i+1][j+1] = 0;
			}
		}
	}

	REP(i,n+1) dpite(ALL(dp[i]));
	DEBUG(endl);
	REP(i,n) dpite(ALL(pre[i]));
	DEBUG(n+1); DEBUG(m);

	vector<int> ope;
	int i = n, j = m;
	while(i != 0 or j != 0){
		int dx, dy;
		tie(dx,dy) = vec[pre[i][j]];
		ope.push_back(pre[i][j]);
		i += dx; j += dy;
	}
	dpite(ALL(ope));
	return dp[n][m];

}


void ios_init(){
	//cout.setf(ios::fixed);
	//cout.precision(12);
#ifdef LOCAL111
	return;
#endif
	ios::sync_with_stdio(false); cin.tie(0);	
}

int main()
{
	ios_init();
	string s,t;
	int n,m;
	while(cin >> n >> m >> s >> t) {
		cout << editDist(s,t) << endl;
	}
	return 0;
}