#include <bits/stdc++.h>
using namespace std;
mt19937 rng(chrono::high_resolution_clock::now().time_since_epoch().count());
const int N = 4005;
string s[N];
int n, m, k, num[N];
long long sum[N][4];
int index(char c) {
if (c == 'A') return 0;
if (c == 'C') return 1;
if (c == 'G') return 2;
return 3;
}
int rand(int l, int r) {
return uniform_int_distribution<int> (l, r)(rng);
}
int calc(int i, int j) {
int res = 0;
for (int x = 0; x < m; x++)
res += s[i][x] != s[j][x];
return res;
}
int main() {
cin.tie(0)->sync_with_stdio(0);
cin >> n >> m >> k;
for (int i = 0; i < n; i++) {
num[i] = rand(1, 1e9);
cin >> s[i];
for (int j = 0; j < m; j++)
sum[j][index(s[i][j])] += num[i];
}
for (int i = 0; i < n; i++) {
long long tmp = 0;
for (int j = 0; j < m; j++)
for (int c = 0; c < 4; c++)
if (index(s[i][j]) != c)
tmp += sum[j][c];
for (int j = 0; j < n; j++)
if (i != j) tmp -= 1ll * num[j] * k;
if (!tmp) cout << i + 1;
}
}
