#include <stdio.h>
#include <stdlib.h>

int main(void){
  int m[100];
  int sm[100];
  int s[100];
  int karv,sugf,sugv, space,l=0,l1=2,arv1,arv2,wh1,i,j,k=0;
  FILE *sisse=fopen("SUG.SIS", "r");
  FILE *valja=fopen("SUG.VAL", "w");
  fscanf(sisse,  "%d%c%d", &karv, &space,&sugf);  
  while(!feof(sisse)){
  fscanf(sisse,  "%d%c%d", &arv1, &space,&arv2);
  m[l]=arv1; m[l+1]=arv2;
    //printf("%d %d\n", m[l], m[l+1]);
  l=l+2;
  }
  j=0;
  while(l1<l){
  if(m[l1]!=m[j] && m[l1+1]!=m[j]){
  if(m[l1]!=m[j+1] && m[l1+1]!=m[j+1]){
  sm[k]=m[l1];
  k++;
  sugv=sugv+1;
  }}j=j+2;l1=l1+2;}
  fclose(sisse);
  fprintf(valja,"%d\n", karv-sugf);
  for(i=0; i<k; i++){
  fprintf(valja,"%d", sm[i]);
  }
  if(sugf-1!=karv-sugf){
  fprintf(valja,"%d", m[0]);}
  fclose(valja);
  return 0;
}