// https://oj.uz/problem/view/BOI18_genetics #include <bits/stdc++.h> using namespace std; mt19937 rng(123); int32_t main() { ios_base::sync_with_stdio(0); cin.tie(0); int n, m, k; cin >> n >> m >> k; vector<string> a(n); for (int i = 0; i < n; i++) cin >> a[i]; vector<int> x(n); for (int i = 0; i < n; i++) x[i] = rng() % (int)(1e9 + 7); map<char, int> mp; mp['A'] = 0, mp['T'] = 1, mp['C'] = 2, mp['G'] = 3; vector<int64_t> sum(n); for (int i = 0; i < m; i++) { vector<int64_t> cnt(4, 0); for (int j = 0; j < n; j++) cnt[mp[a[j][i]]] += x[j]; for (int j = 0; j < n; j++) { for (int k = 0; k < 4; k++) { if (mp[a[j][i]] == k) continue; sum[j] += cnt[k]; } } } int64_t sum_all = accumulate(x.begin(), x.end(), 0ll); for (int i = 0; i < n; i++) { if (sum[i] == 1ll * (sum_all - x[i]) * k) return cout << i + 1, 0; } }