#include <cstdio>
#include <cstring>
#include <iostream>
#include <queue>

using namespace std;

typedef long long int64;
#define PB push_back
#define MP make_pair
#define REP(i,n) for(int i=0;i<int(n);++i)
#define FOR(i,a,b) for(int i=int(a);i<=int(b);++i)
#define FORD(i,a,b) for(int i=int(a);i>=int(b);--i)
#define debug(x) cout<<(#x)<<":"<<(x)<<endl
#define sqr(x) ((x)*(x))

const int dx[4] = {-1, 0, 1, 0};
const int dy[4] = {0, -1, 0, 1};

struct State {
	int x, y, d, v;
	State() {}
	State(int xx, int yy, int dd, int vv): x(xx), y(yy), d(dd), v(vv) {}
};

#define N 55
queue<State> q;
int dis[N][N][4][7], r, c;
char a[N][N], st[N];

inline bool inside(int x, int y) {
	return 0<=x&&x<r&&0<=y&&y<c;
}

void test(int x, int y, int v, int d, int dep) {
	
	// printf("x = %d, y = %d, v = %d, d = %d\n", x, y, v, d);
	bool neg = (v < 0);
	if (neg) v = -v, d = (d+2)&3;
	int nx = x, ny = y, nv = v;
	while (nv--) {
		nx += dx[d], ny += dy[d];
		if (!inside(nx, ny) || a[nx][ny] == 'P') return;
	}
	if (neg) v = -v, d = (d+2)&3;
	// printf("nx = %d, ny = %d, v = %d, d = %d\n", nx, ny, v, d);
	// puts("");
	if (dis[nx][ny][d][v+1] < 0 || dep + 1 < dis[nx][ny][d][v+1]) {
		dis[nx][ny][d][v+1] = dep + 1;
		q.push(State(nx, ny, d, v));
	}
}

int main() {
	int cT, cN;
	freopen("pits.in", "r", stdin);
	gets(st);
	sscanf(st, "%d", &cT);
	FOR(cN, 1, cT) {
		gets(st);
		sscanf(st, "%d%d", &r, &c);
		int sx, sy, tx, ty;
		REP(i, r) {
			gets(a[i]);
			REP(j, c) {
				if (a[i][j] == 'R') sx = i, sy = j;
				if (a[i][j] == 'D') tx = i, ty = j;
			}
		}
		memset(dis, -1, sizeof(dis));
		while (!q.empty()) q.pop();
		q.push(State(sx, sy, 0, 0));
		dis[sx][sy][0][1] = 0;
		// SPFA
		while (!q.empty()) {
			State u = q.front();
			q.pop();
			int x = u.x, y = u.y, d = u.d, v = u.v, nd, nv;
			int dep = dis[x][y][d][v+1];
			if (v == 0) test(x, y, 1, d, dep);
			if (v == 0) test(x, y, -1, d, dep);
			if (v > 0 && v < 5) test(x, y, v+1, d, dep);
			if (v > 0) test(x, y, v-1, d, dep);
			test(x, y, 0, d, dep);
			if (v == 0) test(x, y, 0, (d+1)&3, dep);
			if (v == 0) test(x, y, 0, (d+3)&3, dep);
			test(x, y, v, d, dep);
		}
		int ans = -1;
		REP(d, 4) {
			int t = dis[tx][ty][d][1];
			if (t >= 0 && (ans < 0 || t < ans)) ans = t;
		}
		printf("Data Set %d:\n", cN);
		if (ans < 0) puts("Impossible"); else printf("%d\n", ans);
		puts("");
	}
}