#include<stdio.h>
long mod(long a)
{ if(a<0) a=-a;
  return a;
}
long minim(long a,long b)
{ if(a<b) return a;
  return b;
}
char c;
int xi,yi,xo,yo,x,y,n,m,j,l,a[1002][1002],mt[1002][1002],stx[50000],sty[50000],cx[50000],cy[50000];
long i,k,o;
FILE *f,*g;
int main()
{ f=fopen("barbar.in","r"); g=fopen("barbar.out","w");
  fscanf(f,"%d%d",&n,&m);
  for(i=1;i<=n;i++)
   { fscanf(f,"%c",&c);
     for(j=1;j<=m;j++)
      { fscanf(f,"%c",&c);
	if(c=='.') { a[i][j]=-3; mt[i][j]=-3; }
	else if(c=='*') a[i][j]=-1;
	else if(c=='D') { a[i][j]=-3; mt[i][j]=-3; k++; stx[k]=i; sty[k]=j; }
	else if(c=='I') { a[i][j]=-3; xi=i; yi=j; mt[i][j]=-3; }
	else if(c=='O') { a[i][j]=-3;xo=i; yo=j; mt[i][j]=-3;}
      }
   }
  for(i=1;i<=k;i++)for(j=1;j<=n;j++) for(l=1;l<=m;l++) if(a[j][l]==-3) a[j][l]=mod(j-stx[i])+mod(l-sty[i]);
  else if(a[j][l]>0) if(mod(j-stx[i])+mod(l-sty[i])<a[j][l]) a[j][l]=mod(j-stx[i])+mod(l-sty[i]);

  k=1; for(i=1;i<=n;i++) { a[i][0]=2000; a[i][m+1]=2000; mt[i][0]=2000; mt[i][m+1]=2000;}
  for(i=1;i<=m;i++) { a[0][i]=2000; a[n+1][i]=2000; mt[0][i]=2000; mt[n+1][i]=2000;}
  stx[k]=xi; sty[k]=yi; mt[xi][yi]=a[xi][yi];
  while(k)
   { o=0;
     for(i=1;i<=k;i++)
      { x=stx[i]; y=sty[i];
	if(a[x][y+1]!=-1)
	 { if(mt[x][y+1]==-3) { mt[x][y+1]=minim(mt[x][y],a[x][y+1]); o++; cx[o]=x; cy[o]=y+1; }
	   else if(mt[x][y]>mt[x][y+1]&&mt[x][y]<=a[x][y+1]) { mt[x][y+1]=mt[x][y];
	   o++; cx[o]=x; cy[o]=y+1;}
	 }
	if(a[x][y-1]!=-1)
	 { if(mt[x][y-1]==-3) { mt[x][y-1]=minim(mt[x][y],a[x][y-1]);o++; cx[o]=x; cy[o]=y-1; }
	   else if(mt[x][y]>mt[x][y-1]&&mt[x][y]<=a[x][y-1]) { mt[x][y-1]=mt[x][y];
	   o++; cx[o]=x; cy[o]=y-1;}
	 }
	if(a[x+1][y]!=-1)
	 { if(mt[x+1][y]==-3) { mt[x+1][y]=minim(mt[x][y],a[x+1][y]); o++; cx[o]=x+1; cy[o]=y; }
	   else if(mt[x][y]>mt[x+1][y]&&mt[x][y]<=a[x+1][y]) { mt[x+1][y]=mt[x][y];
	   o++; cx[o]=x+1; cy[o]=y;}
	 }
	if(a[x-1][y]!=-1)
	 { if(mt[x-1][y]==-3) { o++; cx[o]=x-1; cy[o]=y; mt[x-1][y]=minim(mt[x][y],a[x-1][y]);}
	   else if(mt[x][y]>mt[x-1][y]&&mt[x][y]<=a[x-1][y]) { mt[x-1][y]=mt[x][y];
	   o++; cx[o]=x-1; cy[o]=y;}
	 }
      }
     for(i=1;i<=o;i++) { stx[i]=cx[i];sty[i]=cy[i]; }
     k=o;
   }
  fprintf(g,"%d",mt[xo][yo]);
  fclose(g);
  return 0;
}