#pragma GCC optimize ("O3")
#pragma GCC target ("sse4")
#include <bits/stdc++.h>
using namespace std;
typedef long long lo;
typedef pair< lo,lo > PII;
#define fi first
#define se second
#define mp make_pair
#define pb push_back
#define fio() ios_base::sync_with_stdio(false);cin.tie(NULL);cout.tie(NULL)
#define FOR for(int i=1;i<=n;i++)
#define mid ((start+end)/2)
#define ort ((bas+son)/2)
const lo MAX = -1000000000000000000;
const lo MIN = 1000000000000000000;
const lo inf = 1000000000;
const lo KOK = 100000;
const lo LOG = 30;
const lo li = 5005;
const lo mod = 1000000007;
int n,m,b[li],a[li],k,flag,t,dp[li][li],vis[li],mn[li],mx[li];
int cev;
string s[li];
vector<int> v[li],v1;
int main(void){
cin>>n>>m>>k;
FOR{
cin>>s[i];
mn[i]=inf;
}
for(int i=1;i*i<=n*2;i++){
for(int j=1;j<=n;j++){
cev=0;
if(j==i)continue;
for(int jj=0;jj<m;jj++){
if(s[i][jj]!=s[j][jj])cev++;
}
mn[j]=min(mn[j],cev);
mx[j]=max(mx[j],cev);
mn[i]=min(mn[i],cev);
mx[i]=max(mx[i],cev);
}
}
FOR{
//~ cout<<mn[i]<<" : ; "<<mx[i]<<endl;
if(mn[i]==k && mx[i]==k){printf("%d\n",i);return 0;}
}
return 0;
}
