package Strings; import java.util.Scanner; public class RichieRich { public static void main(String[] args) { Scanner in = new Scanner(System.in); int n = in.nextInt(); int k = in.nextInt(); char c[] = in.next().toCharArray(); boolean flag=true; boolean v[]=new boolean[n]; label: for(int i=0;i<=n/2;i++){ if(c[i]>c[n-1-i]){ if(k>0){ k--; c[n-1-i]=c[i]; v[n-1-i]=true; } else{ flag=false; break label; } } else if(c[i]0){ k--; c[i]=c[n-1-i]; v[i]=true; } else{ flag=false; break label; } } } if(!flag){ System.out.println("-1"); } else{ for(int i=0;i<=n/2;i++){ if(c[i]!='9'&&c[n-1-i]!='9'){ if(k>0&&(v[i]||v[n-1-i])){ k--; c[i]='9'; c[n-1-i]='9'; } else if(k>0&&i==n/2){ k--; c[i]='9'; c[n-1-i]='9'; } else if(k>1){ k-=2; c[i]='9'; c[n-1-i]='9'; } } } System.out.println(c); } } }