#include<bits/stdc++.h>
using namespace std;
//#pragma GCC optimize("O3")


#define rep(i,n) for(ll i=0;i<n;i++)
#define repl(i,l,r) for(ll i=(l);i<(r);i++)
#define per(i,n) for(ll i=(n)-1;i>=0;i--)
#define perl(i,r,l) for(ll i=r-1;i>=l;i--)
#define fi first
#define se second
#define ins insert
#define pqueue(x) priority_queue<x,vector<x>,greater<x>>
#define all(x) (x).begin(),(x).end()
#define CST(x) cout<<fixed<<setprecision(x)
#define rev(x) reverse(x);
using ll=unsigned long long;
using vl=vector<ll>;
using vvl=vector<vector<ll>>;
using pl=pair<ll,ll>;
using vpl=vector<pl>;
using vvpl=vector<vpl>;
const ll MOD=1000000007;
const ll MOD9=998244353;
const int inf=1e9+10;
const ll INF=4e18;
//const ll dy[9]={1,0,-1,0,1,1,-1,-1,0};
//onst ll dx[9]={0,1,0,-1,1,-1,1,-1,0};
template <typename T> inline bool chmax(T &a, T b) {
  return ((a < b) ? (a = b, true) : (false));
}
template <typename T> inline bool chmin(T &a, T b) {
  return ((a > b) ? (a = b, true) : (false));
}

int main(){
  ll h,w,n,p;cin >> h >> w >> n >> p;
  vl x(n),y(n);
  vector<string> v(n);
  rep(i,n){
    cin >> x[i] >> y[i] >> v[i];
  }
  ll ans=0,score=0;
  rep(bit,1<<n){
    if(__builtin_popcount(bit)>p)continue;
    vvl dp(h+1,vl(w+1));dp[0][0]=1;
    rep(i,h+1){
      rep(j,w+1){
        rep(k,n){
          if(!(bit>>k&1)){
            if(x[k]==i&&y[k]==j)dp[i][j]=0;
          }
        }
        if(i<h){
          dp[i+1][j]+=dp[i][j];
        }
        if(j<w){
          dp[i][j+1]+=dp[i][j];
        }
      }
    }
    if(chmax(score,dp[h][w]))ans=bit;
  }
  cout << score << endl;
  rep(i,n){
    if(ans>>i&1)cout << v[i] << endl;
  }
}