#include<bits/stdc++.h>
using namespace std;
const int N=4150;
int n,m,k,curr,test,cnt,perm[N],seed[N];
string ipt,a[N];
set<pair<int,int>> ppl,all;
mt19937 rng(1234);
int random(int l,int r){
return uniform_int_distribution<int>(l,r)(rng);
}
int choose(set<pair<int,int>> &s){
auto it=s.upper_bound({random(1,1e9),0});
if (it==s.end()) it=s.begin();
return (*it).second;
}
int main(){
cin>>n>>m>>k;
iota(perm,perm+m,0);
shuffle(perm,perm+m,rng);
for (int i=1;i<=n;i++){
cin>>ipt;
a[i]=ipt;
for (int j=0;j<m;j++) a[i][j]=ipt[perm[j]];
seed[i]=random(1,1e9);
ppl.insert({seed[i],i});
all.insert({random(1,1e9),i});
}
while (ppl.size()>1){
curr=choose(ppl);
do{
test=choose(all);
} while (test==curr);
cnt=0;
for (int i=0;i<m;i++){
cnt+=(a[curr][i]!=a[test][i]);
if (cnt>k||cnt+(m-i-1)<k) break;
}
if (cnt!=k) ppl.erase({seed[curr],curr});
}
cout<<choose(ppl)<<"\n";
}
