#include<cstdio>
#include<vector>
#include<queue>
#include<cstring>
using namespace std;const int maxn = 150;//状态个数的估计是非常重要的
struct state
{int fir,sec,thir;state(int a = 0,int b = 0,int c = 0):fir(a),sec(b),thir(c){}
};int dist[maxn][maxn][maxn];
int start[3];
int End[3];
char G[20][20];
vector<int>Next[150];
int cnt = 0;
int dr[] = {-1,0,1,0};
int dc[] = {0,1,0,-1};
bool read_input()
{cnt = 0;memset(dist,0,sizeof(dist));//start.clear();//End.clear();for(int i = 0;i < 150;i++){Next[i].clear();}int row,col,num_ghost;scanf("%d%d%d\n",&col,&row,&num_ghost);if(!row){return false;}//cnt代表此时用多少个可以走的cellfor(int i = 0;i < row;i++){fgets(G[i],20,stdin);for(int j = 0;j < col;j++){if(G[i][j] != '#'){if(G[i][j] <= 'Z' && G[i][j] >= 'A'){End[G[i][j] - 'A'] = cnt;//End.push_back(cnt);
                }else if(G[i][j] <= 'z' && G[i][j] >= 'a'){start[G[i][j] - 'a'] = cnt;}G[i][j] = cnt;cnt++;}}}for(int r = 0;r < row;r++){for(int c = 0;c < col;c++){if(G[r][c] != '#'){Next[G[r][c]].push_back(G[r][c]);for(int k = 0;k < 4;k++){if(G[r + dr[k]][c + dc[k]] != '#'){Next[G[r][c]].push_back(G[r + dr[k]][c + dc[k]]);}}}}}if(num_ghost == 1){Next[cnt + 1].push_back(cnt + 1);Next[cnt + 2].push_back(cnt + 2);start[1] = cnt + 1;start[2] = cnt + 2;End[1] = cnt + 1;End[2] = cnt + 2;//start.push_back(cnt + 1);//start.push_back(cnt + 2);
    }else if(num_ghost == 2){Next[cnt + 1].push_back(cnt + 1);start[2] = cnt + 1;End[2] = cnt + 1;//start.push_back(cnt + 1);
    }return 1;
}void BFS()
{memset(dist,-1,sizeof(dist));queue<state>Q;state u(start[0],start[1],start[2]);Q.push(u);dist[start[0]][start[1]][start[2]] = 0;while(!Q.empty()){state u = Q.front();Q.pop();if(u.fir == End[0] && u.sec ==End[1] && u.thir == End[2]){printf("%d\n",dist[End[0]][End[1]][End[2]]);return ;//找到了答案
        }int fir1 ,sec1,thir1;for(int i = 0;i < Next[u.fir].size();i++){fir1 = Next[u.fir][i];for(int j = 0; j < Next[u.sec].size();j++){sec1 = Next[u.sec][j];if(fir1 == sec1 || (u.fir == sec1 && u.sec == fir1))continue;for(int k = 0;k < Next[u.thir].size();k++){thir1 = Next[u.thir][k];if(fir1 == thir1 || (u.fir == thir1 && u.thir == fir1))continue;if(sec1 == thir1 || (u.thir == sec1 && u.sec == thir1))continue;state v(fir1,sec1,thir1);if(dist[fir1][sec1][thir1] < 0 ){dist[fir1][sec1][thir1] = dist[u.fir][u.sec][u.thir] + 1;Q.push(v);}}}}}}int main()
{freopen("input.txt","r",stdin);freopen("output.txt","w",stdout);while(read_input()){BFS();}return 0;
}