// Src : Vux2Code
/* Note :
*/
#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
typedef long double ld;
typedef pair<ll, ll> pll;
#define fi first
#define se second
#define pusb push_back
#define popb pop_back
#define pusf push_front
#define popf pop_front
#define vec3d vector<vector<vector<ll>>>
#define vec2d vector<vector<ll>>
#define vec1d vector<ll>
vec3d set3 (ll x, ll y, ll z, ll val = 0) {return vec3d (x, vec2d (y, vec1d (z, val)));}
vec2d set2 (ll x, ll y, ll val = 0) {return vec2d (x, vec1d (y, val));}
template<typename T>
using rvs_pq = std::priority_queue<T, std::vector<T>, std::greater<T>>;
#define forinc(i, a, b) for (ll i = (a); i <= (b); ++i)
#define fordec(i, a, b) for (ll i = (a); i >= (b); --i)
#define foreach(i, j) for (ll i : (j))
#define all(a) (a).begin (), (a). end ()
#define uni(a) (a).erase(unique((a).begin(), (a). end ()), (a). end ())
const ll maxN = 41e2 + 5, maxLog = 20, inf64 = 1e18, inf32 = 1e9, mod = 1e9 + 7;
void maxi(ll &x, ll y) { x = max(x, y); }
void mini(ll &x, ll y) { x = min(x, y); }
/* ---------HASHING-------- */
// const base = 31, mod2 = 1e9 + 9;
/* ---------BITMASK-------- */
// ll count(ll x) { return __builtin_popcountll(x); }
// ll fst(ll x) { return 63 - __builtin_clzll(x); }
// ll last(ll x) { return __builtin_ctzll(x); }
// bool bit(ll x, ll y) { return ((x >> y) & 1); }
ll t = 1;
ll n, m, k, w [maxN], sumw, sum [maxN];
char a [maxN] [maxN];
map <char, ll> mp [maxN];
void solve() {
cin >> n >> m >> k;
forinc (i, 1, n) {
forinc (j, 1, m) {
cin >> a [i] [j];
}
}
random_device rd;
mt19937 gen (124523);
uniform_int_distribution<> distr (1, INT_MAX);
forinc (i, 1, n) {
w [i] = distr (gen);
sumw += w [i];
}
forinc (i, 1, n) {
forinc (j, 1, m) {
mp [j] [a [i] [j]] += w [i];
}
}
forinc (i, 1, n) {
forinc (j, 1, m) {
for (pll k : mp [j]) {
if (k. fi != a [i] [j]) sum [i] += k. se;
}
}
}
forinc (i, 1, n) {
if (sum [i] == k * (sumw - w [i])) {
cout << i;
return;
}
}
}
int main() {
ios::sync_with_stdio(0);
cin.tie(0);
cout.tie(0);
// #define TASK "E:/Code/CP/task"
// if (fopen (TASK".inp", "r")) {
// freopen (TASK".inp", "r", stdin);
// freopen (TASK".out", "w", stdout);
// }
// cin >> t;
while (t--) solve();
}
