#include <bits/stdc++.h>
using namespace std;
typedef long long ll;

ll calc(string& A, string& B) {
    ll ans = 0;
    for(ll i = 0; i < A.size(); i++) ans += (A[i]!=B[i]);
    return ans;
}

int main() {
    ll N,M,K; cin >> N >> M >> K;

    vector<string> Ss(N);
    for(ll i = 0; i < N; i++) cin >> Ss[i];

    ll ans;
    for(ll i = 0; i < N; i++) {
        ll ct = 0;
        ll tr = 0;
        for(ll j = 0; j < 60; j++) {
            ll i2 = (i+1+j)%N;
            if(i2 != i) {
                tr++;
                if(calc(Ss[i],Ss[i2]) == K) ct++;
            }
        }

        if(tr == ct) ans = i+1;
    }

    cout << ans << endl;


}