#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
#define pb push_back
mt19937 rng(chrono::steady_clock::now().time_since_epoch().count());
const int maxn5 = 3e5 + 10;
string s[maxn5];
int av[maxn5], per[maxn5];
int n, m, k;
inline bool ok(int i, int j){
int cnt = 0;
for(int z = 0; z < m && cnt <= k; z++)
cnt += (s[i][z] != s[j][z]);
return cnt == k;
}
inline void check(int v){
for(int i = 0; i < n; i++)
av[i] = i;
shuffle(av, av + n, rng);
for(int i = 0; i < n; i++)
if(v != av[i] && !ok(v, av[i]))
return;
cout << v + 1 << endl;
exit(0);
}
int main(){
ios_base::sync_with_stdio(false); cin.tie(0); cout.tie(0);
cin >> n >> m >> k;
for(int i = 0; i < n; i++){
cin >> s[i];
per[i] = i;
}
int sz = n;
while(true){
int id = rng() % sz;
check(per[id]);
for(int i = id + 1; i < sz; i++)
per[i - 1] = per[i];
sz--;
}
}
