#pragma GCC optimize("Ofast,unroll-loops")
#pragma GCC target("avx2")
#include <iostream>
#include <fstream>
#include <vector>
#include <queue>
#include <utility>
#include <algorithm>
#include <bitset>
int x, y, tgt;
char str[4105][4105];
inline int dist(char* a, char* b) {
int ret = 0;
for (int i = 0; i < y; ++i) {
ret += (a[i]==b[i]);
}
return y - ret;
}
int main() {
std::ios_base::sync_with_stdio(false);
std::cin.tie(NULL);
std::cout.tie(NULL);
std::cin >> x >> y >> tgt;
for (int i = 0; i < x; i++) {
std::cin >> str[i];
}
for (int i = 0; i < x; i++) {
bool ok = 1;
for (int j = 0; j < x && ok; j++) {
if (i==j) {
continue;
}
ok &= (dist(str[i],str[j])==tgt);
}
if (ok) {
std::cout << i+1 << "\n";
break;
}
}
}
