#include <fstream>
#include <queue>
#define mp make_pair
#define ZID -1
#define DRAGON 2

using namespace std;

ifstream fin("barbar.in");
ofstream fout("barbar.out");

void lee();

int dx[] = {-1,0,1,0};
int dy[] = {0,1,0,-1};
int n, m, minim, dist[1005][1005], a[1005][1005];
pair<int,int> start, stop;
queue<pair<int,int> > Q;

class mycomparison
{
public:
  bool operator() (const pair<int,int>& lhs, const pair<int,int>&rhs) const
  {
    return (dist[lhs.first][lhs.second]<dist[rhs.first][rhs.second]);
  }
};

priority_queue<pair<int,int>,vector<pair<int,int> >, mycomparison> H;

int main()
{
    char c;
    int i, j, l9, c9;
    pair<int,int> aux;

    fin >> n >> m;
    for (i=1;i<=n;i++)
        for (j=1;j<=m;j++)
        {
            fin >> c;
            if (c == '*')
                a[i][j] = ZID;
            else if (c == 'D')
            {
                a[i][j] = DRAGON;
                Q.push(mp(i,j));
            }
            else if (c == 'I')
                start = mp(i,j);
            else if (c == 'O')
                stop = mp(i,j);
        }
    lee();
    H.push(start);
    minim = 5000;
    while (1 && !H.empty())
    {
        aux = H.top();
        minim = min(minim,dist[aux.first][aux.second]);
        if (aux == stop)
            break;
        H.pop();
        for (i=0;i<4;i++)
        {
            l9 = aux.first+dx[i];
            c9 = aux.second+dy[i];
            if (!a[l9][c9])
            {
                H.push(mp(l9,c9));
                a[l9][c9] = 1;
            }
        }
    }
    if (aux == stop)
        fout << minim << '\n';
    else fout << -1 << '\n';
    return 0;
}

void lee()
{
    int i, l9, c9;
    pair<int,int> aux;

    for (i=0;i<=n+1;i++)
        a[i][0] = a[i][m+1] = ZID;
    for (i=0;i<=m+1;i++)
        a[0][i] = a[n+1][i] = ZID;
    while (!Q.empty())
    {
        aux = Q.front();
        Q.pop();
        for (i=0;i<4;i++)
        {
            l9 = aux.first+dx[i];
            c9 = aux.second+dy[i];
            if (!dist[l9][c9] && !a[l9][c9])
            {
                dist[l9][c9] = 1+dist[aux.first][aux.second];
                Q.push(mp(l9,c9));
            }
        }
    }
}