#include<iostream>
#include<string>
#include<queue>
#include<algorithm>

using namespace std;

#define nm 1005
#define pb push_back
#define mkp make_pair
#define inf 1000000000
#define min(a,b)((a)<(b)?(a):(b))
#define max(a,b)((a)>(b)?(a):(b))

int sl,sc,el,ec,dist[nm][nm],pl[4],pc[4],n,m,sdist[nm][nm];
char mat[nm][nm],viz[nm][nm],isin[nm][nm];

queue<pair<int,int> > Qbf;

int main()
{
    int i,j;
    pair<int,int> pii;
    char ch;
    
    freopen("barbar.in","r",stdin);
    freopen("barbar.out","w",stdout);
    
    scanf("%d %d\n",&n,&m);
    
    for(i=1;i<=n;++i)
    {
      for(j=1;j<=m;++j)
      {
        scanf("%c",&ch);
        if(ch=='D')
        {
          mat[i][j]=2;
          continue;
        }          
        
        if(ch=='I')
        {
          sl=i;
          sc=j;
          continue;
        }     
        
        if(ch=='.') continue;
        
        if(ch=='*')
        {
          mat[i][j]=1;
          continue;
        }
        
        if(ch=='O')
        {
          el=i;
          ec=j;
        }
        
      }               
      scanf("\n");
    }
    
    pl[0]=-1;pl[1]=0;pl[2]=1;pl[3]=0;
    pc[0]=0;pc[1]=1;pc[2]=0;pc[3]=-1;
    
    //partea bf
    
    for(i=1;i<=n;++i)
      for(j=1;j<=m;++j)
        if(mat[i][j]==2)
        {
          Qbf.push(mkp(i,j));
          viz[i][j]=1;
          dist[i][j]=0;
        }
        else dist[i][j]=-1;
        
    while(!Qbf.empty())
    {
      pii=Qbf.front();
      Qbf.pop();
      
      int l=pii.first;
      int c=pii.second;
      
      for(i=0;i<4;++i)
      {
        int nl=l+pl[i];
        int nc=c+pc[i];
        
        if(!nl || !nc) continue;
        if(nl>n || nc>m) continue;
        
        if(viz[nl][nc]) continue;
        if(mat[nl][nc]) continue;
        
        dist[nl][nc]=dist[l][c]+1;
        Qbf.push(mkp(nl,nc));
        viz[nl][nc]=1;
      }  
      
    }    
    /*
    for(i=1;i<=n;++i)
    {
      for(j=1;j<=m;++j)
        printf("%d ",dist[i][j]);                         
      printf("\n");
    }
    */
    //partea de bellman ford(sau altceva)
    
    for(i=1;i<=n;++i)
      for(j=1;j<=m;++j)
        sdist[i][j]=-inf;
    
    Qbf.push(mkp(sl,sc));
    sdist[sl][sc]=dist[sl][sc];
    
    isin[sl][sc]=1;
    
    while(!Qbf.empty())
    {
      pii=Qbf.front();
      Qbf.pop();
      
      int l=pii.first;
      int c=pii.second;
      
      isin[l][c]=0;
      
      for(i=0;i<4;++i)
      {
        int nl=l+pl[i];
        int nc=c+pc[i];
        
        if(!nl || !nc) continue;
        if(nl>n || nc>m) continue;
        
        if(mat[nl][nc]) continue;
        
        if(min(sdist[l][c],dist[nl][nc])>sdist[nl][nc])
        {
          sdist[nl][nc]=min(sdist[l][c],dist[nl][nc]);
          if(!isin[nl][nc])
          {
            Qbf.push(mkp(nl,nc));
            isin[nl][nc]=1;
          }
        }
      }  
      
    }    
    
    if(sdist[el][ec]!=-inf) printf("%d",sdist[el][ec]);
    else printf("-1");
    
    return 0;
}