#include <bits/stdc++.h>
#define For(i,x,y) for (int i=(x);i<=(y);i++)
#define mp make_pair
#define fi first
#define se second
using namespace std;
typedef unsigned long long ull;
typedef pair<int,int> pa;
const int N = 2010;
const ull base = 2333;
int n,m,k;
char s[N];
int main(){
    scanf("%d%d%d",&n,&m,&k);
    map<ull,int>f;
    map<ull,pa>g;
    For(i,1,n){
        scanf("%s",s+1);
        For(j,1,m){
            ull ret=0;
            For(l,(j-1)*k+1,j*k){
                ret=ret*base+s[l];
            }
            f[ret]++;
            g[ret]=mp(i,j);
        }
    }
    for (auto i:f) if (i.se==1){
        printf("%d %d\n",g[i.fi].fi,g[i.fi].se);
    }
}