#include <bits/stdc++.h>
using namespace std;
#define lli long long int
#define X first
#define Y second
#define pb push_back
#define eb emplace_back
#define mp make_pair
#define pii pair<int, int>
#define all(x) x.begin(), x.end()
#define rall(x) x.rbegin(), x.rend()
#define test(args...) abc("[" + string(#args) + "]", args)
void abc() {cerr << endl;}
template <typename T, typename ...U> void abc(T a, U ...b) {
cerr << a << ' ', abc(b...);
}
template <typename T> void printv(T l, T r) {
while (l != r) cout << *l << " \n"[++l == r];
}
const int mod = 1e9 + 7, N = 200000;
int main () {
ios::sync_with_stdio(false);
cin.tie(0);
int n, m, k;
cin >> n >> m >> k;
vector <string> s(n);
for (int i = 0; i < n; ++i) cin >> s[i];
for (int ans = 0; ans < n; ++ans) {
bool is = true;
for (int i = 0; i < n; ++i) if (ans != i) {
int cnt = k;
for (int j = 0; j < m; ++j) cnt -= s[i][j] != s[ans][j];
is &= !cnt;
}
if (is) return cout << ans + 1 << endl, 0;
}
}
