#include <iostream>
#include <cstdio>
#include <algorithm>
#include <vector>
#include <string>
#include <cctype>
#include <cstdlib>
#include <cstring>
using namespace std;

#define FOR(i,N) for(int i=0;i<N;i++)

int N,M,K;
char S[22][22],I[22][22];
pair<char, char> D[60];
int sols;

void back(int kolko){

    //skusime, ci sa vsetky daju este nasadit

    if (kolko == K){
        sols++;
        if(sols==1){
            FOR(i,N){
                FOR(j,M) printf("%c",S[i][j]);
                printf("\n");
            }            
        }
        return;
    }

    for(int l=kolko; l < K; l++){
        //da sa l-ta polozit
        bool found = false;
        FOR(i,N)FOR(j,M-1){
            if ( (S[i][j] == D[l].first && S[i][j+1] == D[l].second) 
                || (S[i][j] == D[l].second && S[i][j+1] == D[l].first) ) found = true;
            if (found) break;
        }
        FOR(i,N-1)FOR(j,M){
            if ( (S[i][j] == D[l].first && S[i+1][j] == D[l].second) 
                    || (S[i][j] == D[l].second && S[i+1][j] == D[l].first) ) found = true;
            if (found) break;
        }
        if (!found) return;
    }

    //vodorovne pridanie
    FOR(i,N)FOR(j,M-1){
        if ( (S[i][j] == D[kolko].first && S[i][j+1] == D[kolko].second) 
                || (S[i][j] == D[kolko].second && S[i][j+1] == D[kolko].first)){
            S[i][j] = '[';
            S[i][j+1] = ']';
            back(kolko+1);
            S[i][j] = I[i][j];
            S[i][j+1] = I[i][j+1];
        }
    }

    //zvisle pridanie
    FOR(i,N-1)FOR(j,M){
        if ( (S[i][j] == D[kolko].first && S[i+1][j] == D[kolko].second) 
                || (S[i][j] == D[kolko].second && S[i+1][j] == D[kolko].first)){
            S[i][j] = 'n';
            S[i+1][j] = 'u';
            back(kolko+1);
            S[i][j] = I[i][j];
            S[i+1][j] = I[i+1][j];
        }
    }

    return;
}

int x,y;

int pocm[10],poci[10];

int main(){
    while(true){
        scanf("%d %d %d", &N,&M,&K);
        if (N==0) break;
        memset(pocm,0,sizeof(pocm));
        memset(poci,0,sizeof(poci));
        FOR(i,K){
            scanf("%d %d ",&x, &y);
            poci[x]++;
            poci[y]++;
            D[i].first = x+'0';
            D[i].second = y+'0';
        }
        //vstup!
        FOR(i,N){
            FOR(j,M){
                char c;
                scanf("%c ",&c);
                S[i][j] = c;
                I[i][j] = c;
                if (c!='X') pocm[c-'0']++;
            }
        }
        bool bad = false;
        FOR(i,10) if (pocm[i] != poci[i]){
            bad = true;
        }
        if (bad){
            printf("impossible\n\n");
            continue;
        }
        sols = 0;
        back(0);
        if (sols == 0) printf("impossible\n\n");
        else printf("%d\n\n",sols-1);
    }

    return 0;
}