#include <set>
#include <map>
#include <list>
#include <queue>
#include <cmath>
#include <time.h>
#include <random>
#include <bitset>
#include <vector>
#include <cstdio>
#include <stdio.h>
#include <iomanip>
#include <assert.h>
#include <stdlib.h>
#include <memory.h>
#include <string.h>
#include <iostream>
#include <algorithm>
#include <unordered_map>

using namespace std;

typedef long long ll;
typedef unsigned long long ull;

#define mk make_pair
#define fi first
#define se second

inline int read(){
	int t = 0,f = 1;
	register char c = getchar();
	while (c < 48 || c > 57) f = (c == '-') ? -1 : 1,c = getchar();
	while (c >= 48 && c <= 57) t = (t << 1) + (t << 3) + (c ^ 48),c = getchar();
	return f * t;
}

inline int reads(char *s){
	int t = 0;
	register char c = getchar();
	while (c < 'a' || c > 'z') c = getchar();
	while (c >= 'a' && c <= 'z') s[++t] = c,c = getchar();
	return t;
}

const int N = 1e6 + 10,K = 1000 + 10,P = 131,V = 26;
int T,n,m,k,dp[K][K << 1],xxx,yyy;
char s[N],t[N];
ull shsh[N],thsh[N],pw[N],w[P + 10];
pair <int,int> fr[K][K << 1];

mt19937 myrand((int)time(0));

inline int rnd(int l,int r) {return myrand() % (r - l + 1) + l;}

inline ull chash(ull *hs,int l,int r){
	return hs[r] - hs[l - 1] * pw[r - l + 1];
}

void upd(int x,int y,int kk,int xx,int yy){
	if (x > n || y > m) return ;
	int l = 0,r = min(n - x,m - y);
	if (r && s[x + 1] != t[y + 1]) r = 0;
	while (l < r){
		int mid = (l + r + 1) >> 1;
		if (!mid || chash(shsh,x + 1,x + mid) == chash(thsh,y + 1,y + mid)) l = mid;
		else r = mid - 1;
	}
	x += l,y += l;
	int i = kk,j = x - y + k;
	if (x > dp[i][j]){
		if (xx == -1) xxx = i,yyy = j;
		dp[i][j] = x,fr[i][j] = mk(xx,yy);
	}
}

int cnt = 0;

namespace chk{
	bool ok = 1;
	char s[N];
	int n;
	void replace(int i,char c){
		if (i > n) ok = 0;
		s[i] = c;
	}
	void del(int i){
		if (i < 0 || i > n) ok = 0;
		for (int p = i;p < n;p++) s[p] = s[p + 1];
		--n;
	}
	void ins(int i,char c){
		if (i < 0 || i > n + 1) ok = 0;
		for (int p = n;p >= i;p--) s[p + 1] = s[p];
		s[i] = c;
		++n;
	}
}

void out(int x,int y){
	if (x == xxx && y == yyy) return ;
	if (fr[x][y].fi == -1) return ;
	int xx = fr[x][y].fi,yy = fr[x][y].se;
	out(xx,yy);
	int i = dp[x][y],j = i - (y - k);
	int ii = dp[xx][yy],jj = ii - (yy - k);
	if (y == yy){
		printf("REPLACE %d %c\n",cnt + ii + 1,t[jj + 1]);
		chk::replace(cnt + ii + 1,t[jj + 1]);
	}
	if (y == yy - 1){
		printf("INSERT %d %c\n",cnt + ii + 1,t[jj + 1]);
		chk::ins(cnt + ii + 1,t[jj + 1]);
		++cnt;
	}
	if (y == yy + 1){
		printf("DELETE %d\n",cnt + ii + 1);
		chk::del(cnt + ii + 1);
		--cnt;
	}
}

void runchk(){
	bool f = 1;
	if (m != chk::n) f = 0;
	for (int i = 1;i <= m;i++) if (t[i] != chk::s[i]) f = 0;
	if (!f || !chk::ok){
		puts("WA!!!");
		printf("%d %d %d\n",n,m,k);
		for (int i = 1;i <= n;i++) putchar(s[i]);puts("");
		for (int i = 1;i <= m;i++) putchar(t[i]);puts("");
		exit(0);
	}
}

void solve(){
	cnt = 0;
	n = read(),m = read(),k = read();
	reads(s),reads(t);
	// for (int i = 1;i <= n;i++) s[i] = rnd(0,V) + 'a';
	// for (int i = 1;i <= m;i++) t[i] = rnd(0,V) + 'a';
	for (int i = 1;i < P;i++) w[i] = i;
	shuffle(w + 1,w + P,myrand);
	pw[0] = 1;
	for (int i = 1;i <= max(n,m);i++) pw[i] = pw[i - 1] * P;
	auto ghash = [&](ull *hs,char *s,int n){
		for (int i = 1;i <= n;i++) hs[i] = hs[i - 1] * P + w[s[i] - 'a' + 1];
	};
	ghash(shsh,s,n),ghash(thsh,t,m);
	for (int i = 0;i <= k;i++) for (int j = 0;j <= (k << 1);j++) dp[i][j] = -1,fr[i][j] = mk(-1,-1);
	// dp[0][k] = 0;
	upd(0,0,0,-1,-1);
	for (int i = 0;i < k;i++){
		for (int j = 0;j <= (k << 1);j++){
			int x = dp[i][j],y = x - (j - k);
			if (x < 0 || y < 0) continue;
			upd(x + 1,y + 1,i + 1,i,j);
			upd(x,y + 1,i + 1,i,j);
			upd(x + 1,y,i + 1,i,j); 
		}
	}
	int j = n - m + k;
	bool f = 0;
	for (int i = 0;i <= k;i++) f |= (dp[i][j] == n);
	if (!f) {puts("NO");return ;}
	for (int i = 1;i <= n;i++) chk::s[i] = s[i];
	// chk::n = n; 
	// chk::ok = 1;
	puts("YES");
	for (int i = 0;i <= k;i++){
		if (dp[i][j] == n){
			printf("%d\n",i);
			out(i,j);
			// runchk();
			return ;
		}
	}
}

int main(){
#ifndef ONLINE_JUDGE
	freopen("in.in","r",stdin);
	freopen("out.out","w",stdout);
#endif
	T = read();
	while (T--) solve();
	// n = m = 100,k = 50;
	// while (1) solve();
	return 0;
}