#include "bits/stdc++.h"
using namespace std;
#define ll long long
#define SZ(s) (int)s.size()
int n, m, k1;
bitset <4101> st[4101], st1;
string s1;
int main(){
ios::sync_with_stdio(false); cin.tie(nullptr);
cin >> n >> m >> k1;
if(n > 100){
for(int i = 1; i <= n; i++){
cin >> s1;
for(int j = 0; j < m; j++){
if(s1[j] == 'A') st[i][j] = 1;
}
}
vector <int> vis(n+1,0);
for(int i = 1; i <= n; i++){
bool tr = 0;
if(vis[i]) continue;
for(int j = 1; j <= n; j++){
if(i == j) continue;
st1 = (st[i] ^ st[j]);
int cn = st1.count();
if(cn != k1){
tr = 1;
vis[j] = 1;
break;
}
}
if(!tr){
cout << i;
exit(0);
}
}
}
string s[n+1];
for(int i = 1; i <= n; i++){
cin >> s[i];
}
for(int i = 1; i <= n; i++){
bool tr = 0;
for(int j = 1; j <= n; j++){
int cnt = 0;
if(i == j) continue;
for(int i1 = 0; i1 < m; i1++){
cnt += (s[i][i1] != s[j][i1]);
}
if(cnt != k1){
tr = 1;
break;
}
}
if(!tr){
cout << i;
exit(0);
}
}
}
