#include<iostream>
#include<vector>
#include<string>
#include<algorithm>	
#include<map>
#include<set>
#include<utility>
#include<cmath>
#include<cstring>
#include<queue>
#include<stack>
#include<cstdio>
#include<sstream>
#include<iomanip>
#include<assert.h>
#define loop(i,a,b) for(int i=a;i<b;i++) 
#define rep(i,a) loop(i,0,a)
#define pb push_back
#define mt make_tuple
#define all(in) in.begin(),in.end()
#define shosu(x) fixed<<setprecision(x)
using namespace std;
//kaewasuretyuui
typedef long long ll;
typedef pair<int,int> pii;
typedef vector<ll> vi;
typedef vector<vi> vvi;
typedef vector<pii> vp;
typedef vector<vp> vvp;
typedef vector<string> vs;
typedef vector<double> vd;
typedef tuple<int,int,int> tp;
typedef vector<tp> vt;
typedef vector<vd> vvd;
typedef pair<int,pii> pip;
typedef vector<pip>vip;
const double PI=acos(-1);
const double EPS=1e-7;
const int inf=1e8;
const ll INF=1e16;
int dx[]={0,1,0,-1};
int dy[]={1,0,-1,0};
/*
#define MOD 1000000007
int add(int);
bool friends[35]={};

int main(){
	int H,W,K,P;
	int x[35],y[35];
	char N[21][12];
	long long int dp[35][35]={};
	long long int max=0;
	int e=0;
	bool max_friends[35]={};
	cin >> H >> W >> K >> P;
	REP(i,K){cin>>x[i]>>y[i]>>N[i];}
	while(friends[K]==0){
		REP(i,K){e+=friends[i];}
		if(e<=P){
	    	REP(i,H+1){
	    		REP(j,W+1){
	    			dp[i][j]= -1;
	    		}
	    	}
	    	dp[0][0]=1;
	    	REP(i,K){if(friends[i]==0){dp[x[i]][y[i]] = 0;}}
	    	REP(i,H+1){
			    REP(j,W+1){
			    	if(dp[i][j]==-1){
			    	    if(i==0 && dp[0][j-1]!=0){
			    	        dp[i][j]=1;
			    	    }else if(j==0 && dp[i-1][0]!=0){
			    	        dp[i][j]=1;
			    	    }else if(i!=0 && j!=0){
			    	        dp[i][j] = dp[i-1][j]+dp[i][j-1];
			    	    }else{
			    	        dp[i][j]=0;
			    	    }
			    		
				    }   

	    		}
	    	}
//	    	REP(i,H+1){REP(j,W+1){cout<<dp[i][j]<<" ";}cout<<endl;}
	    	if(dp[H][W]>max){
	    		max=dp[H][W];
	    		REP(i,K){max_friends[i]=friends[i];}
	    		//cout << max << endl;
				REP(i,K)cout<<max_friends[i]<<" "	;cout<<endl;
	    	}
    
		}
		e=0;
		add(0);

	}

	cout << max % MOD <<endl;
	REP(i,K){if(max_friends[i]==1){cout<<N[i]<<endl;}}
	return 0;
}

int add(int a){
	if(friends[a]==0){
		friends[a]=1;
	}else{
		friends[a]=0;
		add(a+1);
	}
	return 0;
}

/*/
int main(){
	int h,w,k,p;
	cin>>h>>w>>k>>p;
	assert(1<=h&&h<=32);
	assert(1<=w&&w<=32);
	assert(1<=k&&k<=20);
	assert(0<=p&&p<=k);
	vs nam(k);
	vp in(k);
	rep(i,k)cin>>in[i].first>>in[i].second>>nam[i];
	rep(i,k)assert(1<=nam[i].size()&&nam[i].size()<=10);
	rep(i,k)assert(0<=in[i].first&&in[i].first<=h);
	rep(i,k)assert(0<=in[i].second&&in[i].second<=w);
	rep(i,k)rep(j,k)if(i!=j){
		assert(in[i]!=in[j]);
		assert(nam[i]!=nam[j]);
	}
	vi q(k);
	vi out;
	ll ma=0,co=0;
	rep(i,p)q[k-1-i]=1;
	do{
		vvi dp(h+2,vi(w+2));
		dp[1][1]=1;
		rep(i,h+1)rep(j,w+1){
			if(i+j==0)continue;
			bool h=true;
			rep(r,k)if(!q[r]&&in[r].first==i&&in[r].second==j)h=false;
			if(h)dp[i+1][j+1]=dp[i+1][j]+dp[i][j+1];
		}
		if(ma<dp[h+1][w+1]){
			ma=dp[h+1][w+1];
			out=q;
			co=1;
		}else if(ma==dp[h+1][w+1])co++;
	}while(next_permutation(all(q)));
	assert(co==1);
	cout<<ma%1000000007<<endl;
	rep(i,out.size())if(out[i])cout<<nam[i]<<endl;
}//*/