//https://codeforces.com/contest/1383/submission/98150891
#include<bits/stdc++.h>
using namespace std;

const int nmax=2e3+42,MX=1e7;

int pointer=0;
vector<int> adj[nmax];

pair<int/*to*/,int/*cap*/> active[MX];

void add_edge(int u,int v,int cap)
{
    //cout<<u<<" "<<v<<" "<<cap<<endl;

    adj[u].push_back(pointer);
    active[pointer]={v,cap};
    pointer++;

    adj[v].push_back(pointer);
    active[pointer]={u,0};
    pointer++;
}

int source,sink;

int dist[nmax];

queue< pair<int/*node*/,int/*dist*/> > bfs_queue,idle;

void bfs()
{
    memset(dist,-1,sizeof(dist));

    bfs_queue=idle;

    bfs_queue.push({source,0});

    while(bfs_queue.size())
    {
        pair<int/*node*/,int/*dist*/> tp=bfs_queue.front();
        bfs_queue.pop();

        if(dist[tp.first]!=-1)continue;

        dist[tp.first]=tp.second;

        if(tp.first==sink)return;

        for(auto k:adj[tp.first])
            if(active[k].second&&dist[active[k].first]==-1)bfs_queue.push({active[k].first,tp.second+1});
    }
}

int id[nmax];

void push_flow(int id_edge,int cur)
{

    active[id_edge].second=active[id_edge].second-cur;
    active[id_edge^1].second=active[id_edge^1].second+cur;
}
/*
                pointer_update++;
                before[pointer_update]={adj[node][id[node]],active[adj[node][id[node]]].second};

                pointer_update++;
                before[pointer_update]={adj[node][id[node]]^1,active[adj[node][id[node]]^1].second};

                active[adj[node][id[node]]].second=active[adj[node][id[node]]].second-cur;
                active[adj[node][id[node]]^1].second=active[adj[node][id[node]]^1].second+cur;
*/
int dfs(int node,int mini)
{
    //cout<<"dfs "<<node<<" "<<mini<<endl;

    if(node==sink)return mini;

    int ret=0;

    for(;id[node]<adj[node].size()&&mini;id[node]++)
    {
        if(dist[node]+1==dist[active[adj[node][id[node]]].first]&&active[adj[node][id[node]]].second)
        {
            int to=active[adj[node][id[node]]].first;

            //cout<<node<<" to "<<to<<endl;

            int cur=dfs(active[adj[node][id[node]]].first,min(mini,active[adj[node][id[node]]].second));

            if(cur)
            {
                push_flow(adj[node][id[node]],cur);

                ret=ret+cur;

                mini=mini-cur;

                if(mini==0)break;
            }
        }
    }
    return ret;
}
int flow()
{
    int ret=0;

    while(1)
    {
        //cout<<"ret= "<<ret<<endl;

        /*
        for(auto w:adj[source])
            cout<<active[w].first<<" "<<active[w].second<<endl;
        */

        bfs();

        /*
        for(int i=source;i<=sink;i++)
            cout<<dist[i]<<" ";cout<<endl;
        */

        if(dist[sink]==-1)break;

        for(int i=source;i<=sink;i++)
            id[i]=0;

        while(1)
        {
            int cur=dfs(source,1e9);

            if(cur==0)break;

            ret=ret+cur;
        }

    }

    return ret;
}











int n,m;

char inp[nmax][nmax];

void no()
{
    printf("-1\n");
    exit(0);
}

char read()
{
    char ret=getchar();

    while(ret!='b'&&ret!='g'&&ret!='_')ret=getchar();

    return ret;
}

int main()
{

    freopen("blueandgreen.in","r",stdin);
    freopen("blueandgreen.out","w",stdout);


    scanf("%i%i",&n,&m);
    /*
    n=1000;
    m=1000;
    */
    for(int i=1;i<=n;i++)
        for(int j=1;j<=m;j++)
        {
            inp[i][j]=read();
            //inp[i][j]='_';
        }

    source=0;
    sink=n+m+1;

    int need=0;

    for(int i=1;i<=n;i++)
    {
        int need_blue=m/2,free_blue=0;

        for(int j=1;j<=m;j++)
            if(inp[i][j]=='b')need_blue--;
            else if(inp[i][j]=='_')free_blue++;

        if(need_blue<0||free_blue<need_blue)no();

        add_edge(source,i,need_blue);

        need+=need_blue;
    }

    for(int j=1;j<=m;j++)
    {
        int need_blue=n/2,free_blue=0;

        for(int i=1;i<=n;i++)
            if(inp[i][j]=='b')need_blue--;
            else if(inp[i][j]=='_')free_blue++;

        if(need_blue<0||free_blue<need_blue)no();

        add_edge(j+n,sink,need_blue);
    }

    for(int i=1;i<=n;i++)
        for(int j=1;j<=m;j++)
            if(inp[i][j]=='_')
            {
                add_edge(i,j+n,1);
            }

    //cout<<"pointer= "<<pointer<<endl;

    if(flow()!=need)no();

    for(int i=1;i<=n;i++)
        for(auto j:adj[i])
        {
            if(n+1<=active[j].first&&active[j].first<=n+m&&active[j].second==0)inp[i][active[j].first-n]='b';
        }

    for(int i=1;i<=n;i++)
    {
        for(int j=1;j<=m;j++)
        {
            if(inp[i][j]=='_')inp[i][j]='g';

            printf("%c",inp[i][j]);
        }

        printf("\n");
    }

    return 0;
}