#include<bits/stdc++.h>
using std::cin;
using std::cout;
using u64 = unsigned long long;
const int mod = 998244353;
std::mt19937 gen(20040430);
const int N = 400005;
std::vector<int8_t> v[N];
int sum[N], w[N];
int n, m, k;
bool check(int x) {
	for(int i = 0;i < n;++i) if(i != x) {
		int cnt = 0;
		for(int j = 0;j < m * 4;++j) {
			cnt += v[i][j] * v[x][j];
		}
		if(cnt != k) return 0;
	}
	return 1;
}
int main() {
	std::ios::sync_with_stdio(false), cin.tie(0);
	cin >> n >> m >> k, k = m - k;
	int su = 0;
	for(int i = 0;i < n;++i) {
		w[i] = gen() % mod;
		su = (su + w[i]) % mod;
	}
	for(int i = 0;i < n;++i) {
		v[i].resize(m * 4);
		for(int j = 0;j < m;++j) {
			char c; cin >> c;
			v[i][j * 4 + c % 4] = 1;
		}
		for(int j = 0;j < m * 4;++j) {
			sum[j] = (sum[j] + v[i][j] * w[i]) % mod;
		}
	}
	for(int i = 0;i < n;++i) {
		int dot = 0;
		for(int j = 0;j < m * 4;++j) {
			dot = (dot + v[i][j] * sum[j]) % mod;
			dot = (dot + mod - v[i][j] * v[i][j] * w[i]) % mod;
		}
		if(dot == (u64) (su + mod - w[i]) * k % mod) {
//			std::cerr << "checking" << i  << '\n';
			if(check(i)) {
				cout << i + 1 << '\n';
				return 0;
			}
		}
	}
}