public void prepareNormal() {
    
for(int num= 0 ;num<levels.length;num++){
      int rand=(int) (p.challange * Math.random());
    if(levels[num]!=null){
       int count=0;
        char[][]curr= levels[num].getLevel();
        int length=curr.length;

        for(int i=0;i<length;i++){
            for(int j=0;j<length;j++){
                if(curr[i][j]==' '&&(i==rand||j==rand)){
                    curr[i][j]='*';
                    count++;
                }
            }
        }
    
    }
}
    }