int main(){

  int n;
  char s[1000000];
  int i,j;
  scanf("%d",&n);
  scanf("%s",s);
  if(n==1)printf("NO\n");
  else if (n==2){
    if(s[0]!=s[1]) printf("NO\n");
    else printf("YES\n");
  }
  else if(n==3){
    if(s[0]=='0' && s[1]=='1' && s[2]=='0')printf("NO\n");
    else if(s[0]=='1' && s[1]=='0' && s[2]=='1')printf("NO\n");
    else printf("YES\n");
  }
  else printf("YES\n");
  return 0;
}