#include <iostream>
#include <cstdlib>
#include <cassert>
#include <string>
#include <vector>
using namespace std;
int main() {
cin.sync_with_stdio(false);
int N, M, K;
cin >> N >> M >> K;
vector<vector<int> > strings(N, vector<int>(M));
vector<bool> iscandidate(N, true);
int ncand = N;
string str;
for (int i = 0; i < N; ++i) {
cin >> str;
for (int j = 0; j < M; ++j)
strings[i][j] = (str[j] >> 1) & 3;
}
while (ncand > 1) {
vector<unsigned> weight(N);
unsigned totweight = 0;
for (int i = 0; i < N; ++i) {
weight[i] = rand();
totweight += weight[i];
}
vector<unsigned> count[4];
count[0].assign(M, 0);
count[1].assign(M, 0);
count[2].assign(M, 0);
count[3].assign(M, 0);
for (int i = 0; i < N; ++i) {
unsigned w = weight[i];
for (int j = 0; j < M; ++j) {
count[strings[i][j]][j] += w;
}
}
for (int i = 0; i < N; ++i) {
if (!iscandidate[i]) continue;
unsigned sumdif = 0;
for (int j = 0; j < M; ++j)
sumdif += totweight - count[strings[i][j]][j];
unsigned expectedsumdif = (totweight - weight[i]) * K;
if (sumdif != expectedsumdif) {
iscandidate[i] = false;
--ncand;
}
}
}
int ans = -1;
for (int i = 0; i < N; ++i) {
if (iscandidate[i]) {
ans = i;
}
}
assert(ans != -1);
for (int i = 0; i < N; ++i) if (i != ans) {
int dif = 0;
for (int j = 0; j < M; ++j)
dif += (strings[i][j] != strings[ans][j]);
assert(dif == K);
}
cout << ans + 1 << endl;
return 0;
}
