#include <bits/stdc++.h>
using namespace std;
#include <ext/pb_ds/assoc_container.hpp>
using namespace __gnu_pbds;
template <class T> using Tree = tree<T, null_type, less<T>, rb_tree_tag, tree_order_statistics_node_update>;
//#include <ext/pb_ds/assoc_container.hpp>
//using namespace __gnu_pbds;
//
//typedef tree<int, null_type, less<int>, rb_tree_tag, tree_order_statistics_node_update> ordered_set;
typedef long long ll;
int n, m, k, score[4150], validCount;
string codes[4150], originalCodes[4150];
bitset<4150> isValid;
int main() {
ios_base::sync_with_stdio(0);
cin.tie(0);
//Tree<int> oset;
cin >> n >> m >> k;
for (int i = 0; i < n; i++) {
cin >> codes[i];
originalCodes[i] = codes[i];
//oset.insert(i);
}
isValid.set();
srand(1932);
random_shuffle(codes, codes + n);
for (int i = 0; i < n; i++) {
if (!isValid[i]) continue;
for (int j = 0; j < n; j++) {
if (i == j) continue;
int diffCount = 0;
for (int c = 0; c < m; c++) if (codes[i][c] != codes[j][c]) diffCount++;
if (diffCount != k) {
isValid[i] = isValid[j] = 0;
break;
}
}
if (isValid[i]) return cout << distance(originalCodes, find(originalCodes, originalCodes + n, codes[i])) + 1 << '\n', 0;
}
//srand(2004);
//while (oset.size() > 1) {
// int i = rand() % n, j = rand() % n;
// if (i == j) continue;
// i = *oset.find_by_order(i);
// j = *oset.find_by_order(j);
// int diffCount = 0;
// for (int c = 0; c < m; c++) if (codes[i][c] != codes[j][c]) diffCount++;
// if (diffCount != k) {
// if (n % 2) { oset.erase(i); n--; }
// oset.erase(j);
// n--;
// }
//}
//for (int i = 0; i < n; i++) cerr << "// score[" << i << "] : " << score[i] << '\n';
//cout << *oset.begin() + 1 << '\n';
}
