#include <bits/stdc++.h>
#define int long long
#define sz(a) (int)a.size()
#define all(a) a.begin(), a.end()
#define rall(a) a.rbegin(), a.rend()
using namespace std;
signed main() {
ios_base::sync_with_stdio(false); cin.tie(nullptr);
int n,m,k; cin >> n >> m >> k;
int blocks=(m/64)+1;
vector<vector<int>> a_c(n,vector<int>(blocks+1));
vector<vector<int>> g_t(n,vector<int>(blocks+1));
for (int i = 0; i < n; i++)
{
int j=0;
int bl=0;
while(j<m){
char c; cin >> c;
if(c=='A') a_c[i][bl]+=(1LL<<j);
if(c=='T') g_t[i][bl]+=(1LL<<j);
j++;
if(j%64==0) bl++;
}
}
vector<vector<int>> dist(n,vector<int>(n,0));
vector<vector<int>> dist2(n,vector<int>(n,0));
vector<vector<int>> dist3(n,vector<int>(n,0));
for (int i = 0; i < n; i++)
{
for (int j = i+1; j < n; j++)
{
for (int _k = 0; _k < blocks; _k++)
{
dist[i][j]+=__builtin_popcountll(a_c[i][_k]^a_c[j][_k]);
dist2[i][j]+=__builtin_popcountll(g_t[i][_k]^g_t[j][_k]);
dist3[i][j]+=__builtin_popcountll(g_t[i][_k]&a_c[j][_k]);
dist3[i][j]+=__builtin_popcountll(a_c[i][_k]&g_t[j][_k]);
}
dist[j][i]=dist[i][j];
dist2[j][i]=dist2[i][j];
dist3[j][i]=dist3[i][j];
}
}
for (int i = 0; i < n; i++)
{
bool b=true;
for (int j = 0; j < n; j++)
{
if(i==j) continue;
if((dist[i][j]+dist2[i][j])-dist3[i][j]!=k) { b=false; break; }
}
if(b==true){
cout << i+1 << "\n";
break;
}
}
return 0;
}
