Language: Java

import java.io.InputStream;
import java.io.InputStreamReader;
import java.io.IOException;
import java.io.PrintWriter;
import java.util.ArrayDeque;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.Comparator;
import java.util.Deque;
import java.util.HashMap;
import java.util.InputMismatchException;
import java.util.Map;
import java.util.PriorityQueue;
import java.math.BigInteger;
    
public class Main{

static final InputStream in=System.in;
static final PrintWriter out=new PrintWriter(System.out);
static final int INF=Integer.MAX_VALUE/2;
static final long LINF=Long.MAX_VALUE/2;
static int m,n;
static char[][] flag;
static char[][] emblem;
static final char[] JOI={'J','O','I'};
    
public static void main(String[] args) throws IOException{
InputReader ir=new InputReader(in);
m=ir.nextInt();
n=ir.nextInt();
flag=ir.makeCharMap(m,n);
emblem=ir.makeCharMap(2,2);
int ans=0,sum=0;
int[][] count=new int[m][n];
for(int i=0;i<m;i++) for(int j=0;j<n;j++)count[i][j]=_count(i,j);
for(int i=0;i<m;i++){
for(int j=0;j<n;j++){
int t=count[i-1][j-1]+count[i][j-1]+count[i][j]+count[i-1][j];
sum+=t;
}
}
for(int i=0;i<m;i++){
for(int j=0;j<n;j++){
for(int k=0;k<3;k++){
if(flag[i][j]!=JOI[k]){
char c=flag[i][j];
int cnt=sum-4*(count[i-1][j-1]+count[i][j-1]+count[i][j]+count[i-1][j]);
flag[i][j]=JOI[k];
ans+=4*_count(i-1,j-1)+4*_count(i-1,j)+4*_count(i,j-1)+4*_count(i,j);
ans=Math.max(cnt,ans);
flag[i][j]=c;
}
}
}
}
out.println(ans/4);
out.flush();
}

public static int _count(int x,int y){
if(x<0||y<0||x>=m||y>=n) return 0;
if(flag[x][y]==emblem[0][0]&&flag[x+1][y]==emblem[1][0]&&flag[x][y+1]==emblem[0][1]&&flag[x+1][y+1]==emblem[1][1]) return 1;
} 

static class InputReader {
private InputStream in;
private byte[] buffer=new byte[1024];
private int curbuf;
private int lenbuf;

public InputReader(InputStream in) {this.in=in;}
  
public int readByte() {
if(lenbuf==-1) throw new InputMismatchException();
if(curbuf>=lenbuf){
curbuf= 0;
try{
lenbuf=in.read(buffer);
}
catch (IOException e) {
throw new InputMismatchException();
}
if(lenbuf<=0)
return -1;
}
return buffer[curbuf++];
}

public boolean isSpaceChar(int c){return !(c>=33&&c<=126);}

private int skip() {int b; while((b = readByte())!=-1&&isSpaceChar(b)); return b;}

public String next() {
int b=skip();
StringBuilder sb=new StringBuilder();
while(!isSpaceChar(b)){
sb.appendCodePoint(b);
b=readByte();
}
return sb.toString();
}
 
public int nextInt() {
int c=readByte();
while (isSpaceChar(c)) c=readByte();
boolean minus=false;
if (c=='-') {
minus=true;
c=readByte();
}
int res=0;
do{
if(c<'0'||c>'9') throw new InputMismatchException();
res=res*10+c-'0';
c=readByte();
}while(!isSpaceChar(c));
return (minus)?-res:res;
}

public long nextLong() {
int c=readByte();
while (isSpaceChar(c)) c=readByte();
boolean minus=false;
if (c=='-') {
minus=true;
c=readByte();
}
long res = 0;
do{
if(c<'0'||c>'9') throw new InputMismatchException();
res=res*10+c-'0';
c=readByte();
}while(!isSpaceChar(c));
return (minus)?-res:res;
}

public int[] toIntArray(int n){
int[] a=new int[n];
for(int i=0;i<n;i++) a[i]=nextInt();
return a;
}

public char[][] makeCharMap(int m,int n){
char[][] map=new char[m][n];
for(int i=0;i<m;i++) map[i]=next().toCharArray();
return map;
}
}
}

Compiler output:
Main.java:63: error: missing return statement
} 
^
1 error