#include <cstdlib>
#include <cstdio>
#include <cstring>
#include <cctype>

struct tile {
	char a;
	char b;
};

int res;
tile tiles[55];

void place(int t, int M, int N, int K, char g[20][20]) {
	/*printf("Call with t %d\n", t);
	for (int i = 0; i < M; i++) {
		for (int j = 0; j < N; j++)
			printf("%c ", g[i][j]);
		printf("\n");
	}
	printf("\n");
	printf("\n");
*/

	if (t == K) {
		if (res == 0) {
			for (int i = 0; i < M; i++) {
				for (int j = 0; j < N; j++)
					printf("%c ", g[i][j]);
				printf("\n");
			}
		}
		res++;
		return;
	}
	for (int i = 0; i < M; i++) {
		for (int j = 0; j < N; j++) {
			if (g[i][j] == tiles[t].a) {
				if (tiles[t].a != tiles[t].b) {
					if (i < M) {
						if (g[i+1][j] == tiles[t].b) {
							char n[20][20];
							memcpy(n, g, sizeof(char)*20*20);
							n[i][j] = 'n';
							n[i+1][j] = 'u';
							place(t+1, M, N, K, n);
						}
					}
					if (i > 0) {
						if (g[i-1][j] == tiles[t].b) {
							char n[20][20];
							memcpy(n, g, sizeof(char)*20*20);
							n[i][j] = 'u';
							n[i-1][j] = 'n';
							place(t+1, M, N, K, n);
						}
					}
					if (j < N) {
						if (g[i][j+1] == tiles[t].b) {
							char n[20][20];
							memcpy(n, g, sizeof(char)*20*20);
							n[i][j+1] = ']';
							n[i][j] = '[';
							place(t+1, M, N, K, n);
						}
					}
					if (j > 0) {
						if (g[i][j-1] == tiles[t].b) {
							char n[20][20];
							memcpy(n, g, sizeof(char)*20*20);
							n[i][j] = ']';
							n[i][j-1] = '[';
							place(t+1, M, N, K, n);
						}
					}
				}
				else {
					if (i < M) {
							if (g[i+1][j] == tiles[t].b) {
								char n[20][20];
								memcpy(n, g, sizeof(char)*20*20);
								n[i][j] = 'n';
								n[i+1][j] = 'u';
								place(t+1, M, N, K, n);
							}
						}
					if (j < N) {
						if (g[i][j+1] == tiles[t].b) {
							char n[20][20];
							memcpy(n, g, sizeof(char)*20*20);
							n[i][j+1] = ']';
							n[i][j] = '[';
							place(t+1, M, N, K, n);
						}
					}
				}
			}
		}
	}
}

bool solve() {
	res = 0;
	char game[20][20];
	memset(game, 'o', sizeof(char)*20*20);
	int M, N, K;
	scanf("%d %d %d\n", &M, &N, &K);
	if (M == 0) return false;
	
	for (int i = 0; i < K; i++) {
		int a,b;
		scanf("%d %d", &a, &b);
		tiles[i].a = a+'0';
		tiles[i].b = b+'0';
	}
	
	for (int i = 0; i < M; i++) {
		for (int j = 0; j < N; j++) {
			char a;
			scanf("%c", &a);
			if (isdigit(a) || a == 'X')
				game[i][j] = a;
			else j--;
		}
		scanf("\n");
	}
	/*for (int i = 0; i < M; i++) {
		for (int j = 0; j < N; j++)
			printf("%c ", game[i][j]);
		printf("\n");
	}*/
	place(0, M, N, K, game);
	if (!res)
		printf("impossible\n\n");
	else 
		printf("%d\n\n", res-1);
	
	return true;
}

int main(int, char**) {
	while(solve());
	return 0;
}