#include <bits/stdc++.h>
using namespace std;

#pragma GCC optimize("O3,unroll-loops")
// #pragma GCC target("avx2,bmi,bmi2,lzcnt,popcnt")

using ll = long long;
using ld = long double;
using pl = pair<ll, ll>;
using vl = vector<ll>;

#define f first
#define s second

ll n, m, k;

bool bad[100005];
using ul = unsigned long long;
vector<ul> bs[100005];
ll sz;

mt19937 rng(53);

bool cmp(ll a, ll b) {
    ll ans = 0;
    for (ll i = 0; i < sz; i++) ans += __builtin_popcountll(bs[a][i] ^ bs[b][i]);
    // cout << a << " " << b << " " << ans << " " << k << endl;
    return ans == k;
}

int main() {
    cin >> n >> m >> k;
    k *= 2;

    sz = m / 16 + 2;

    for (ll i = 0; i < n; i++) {
        string s; cin >> s;
        bs[i] = vector<ul>(sz);
        for (ll j = 0; j < m; j++) {
            ul v = 1 << (s[j] - 'A');
            bs[i][j / 16] += v << (4 * (j % 16));
        }
    }

    ll s = n;

    vl a(n);
    iota(a.begin(), a.end(), 0);

    while (s > 1) {
        // cout << s << " " << a.size() << endl;
        ll x = rng() % s;
        while (bad[a[x]]) x = rng() % s;
        x = a[x];

        ll y = rng() % n;
        while (x == y) y = rng() % n;

        if (!cmp(x, y)) {
            if (!bad[x]) --s;
            if (!bad[y]) --s;
            bad[x] = bad[y] = 1;
        }

        if (s * 2 <= a.size()) {
            vl b;
            for (ll x: a) if (!bad[x]) b.push_back(x);
            a = b;
            s = a.size();
        }
    }

    cout << a[0] + 1 << '\n';
}