#include <array>
#include <bits/stdc++.h>
#include <queue>
using namespace std;

using ll = long long;
using pii = pair<int, int>;
using pll = pair<ll, ll>;
using vi = vector<int>;
using vl = vector<ll>;
#define rep3(i, a, b, c) for (ll i = (a); i < (b); i += (c))
#define rep2(i, a, b) rep3(i, a, b, 1)
#define rep1(i, n) rep2(i, 0, n)
#define rep0(n) rep1(aaaaa, n)
#define ov4(a, b, c, d, name, ...) name
#define rep(...) ov4(__VA_ARGS__, rep3, rep2, rep1, rep0)(__VA_ARGS__)
#define per(i, a, b) for (ll i = (a) - 1; i >= (b); i--)
#define fore(e, v) for (auto&& e : v)
#define all(a) begin(a), end(a)
#define sz(a) (int)(size(a))
#define lb(v, x) (lower_bound(all(v), x) - begin(v))
#define eb emplace_back

template <typename T, typename S>
bool chmin(T& a, const S& b) {
  return a > b ? a = b, 1 : 0;
}
template <typename T, typename S>
bool chmax(T& a, const S& b) {
  return a < b ? a = b, 1 : 0;
}
const int INF = 1e9 + 100;
const ll INFL = 3e18 + 100;
#define i128 __int128_t
struct _ {
  _() { cin.tie(0)->sync_with_stdio(0), cout.tie(0); }
} __;

int main(){
  int H,W,M;
  cin>>H>>W>>M;
  vector<string> S(H);
  rep(i,H)cin>>S[i];
  vector dist(H,vector(W,vi(10,(int)1e9)));
  using ai3 = array<int, 3>;
  queue<ai3> bfs;
  rep(i,H){
    rep(j,W){
      if(S[i][j]=='S'){
        dist[i][j][0]=0;
        bfs.push(ai3{(int)i,(int)j,0});
      }
    }
  }
  int dx[]={1,0,-1,0};
  int dy[]={0,1,0,-1};
  auto bound_ok=[H,W](int x,int y){
    return x>=0&&x<H&&y>=0&&y<W;
  };
  while(bfs.size()){
    auto [x,y,key]=bfs.front();
    bfs.pop();
    int d=dist[x][y][key];
    rep(i,4){
      int x2=x+dx[i],y2=y+dy[i];
      if(bound_ok(x2, y2)){
        if(S[x2][y2]>='1'&&S[x2][y2]<='9'){
          int k2=S[x2][y2]-'0';
          if(dist[x2][y2][k2]>d+1){
            dist[x2][y2][k2]=d+1;
            bfs.push(ai3{x2,y2,k2});
          }
        }else if(S[x2][y2]>='a'&&S[x2][y2]<='i'){
          if(S[x2][y2]-'a'+1==key && dist[x2][y2][key]>d+1){
            dist[x2][y2][key]=d+1;
            bfs.push(ai3{x2,y2,key});
          }
        }else if(S[x2][y2]!='#'){
          if(dist[x2][y2][key]>d+1){
            dist[x2][y2][key]=d+1;
            bfs.push(ai3{x2,y2,key});
          }
        }
      }
    }
  }
  int ans=1e9;
  rep(i,H){
    rep(j,W){
      if(S[i][j]=='G'){
        rep(k,10){
          chmin(ans,dist[i][j][k]);
        }
      }
    }
  }
  cout<<(ans==1e9?-1:ans)<<'\n';
}