#include<bits/stdc++.h>
using namespace std;
typedef long long ll;
typedef unsigned long long ull;
typedef pair<int,int> P;
#define fi first
#define se second
#define mkp make_pair
#define pb emplace_back
#define popcnt __builtin_popcountll
const int mod = 998244353;
inline ll read(){
	ll x=0, f=1; char ch=getchar();
	while(ch<'0' || ch>'9') { if(ch=='-') f=-1; ch=getchar(); }
	while(ch>='0' && ch<='9') x=x*10+ch-'0', ch=getchar();
	return x*f;
}
inline int lg2(int x){ return 31^__builtin_clz(x); }
inline ll lg2(ll x){ return 63^__builtin_clzll(x); }
inline ll qpow(ll a,ll b){
	ll ans=1, base=a;
	while(b){
		if(b&1) ans=ans*base%mod;
		base=base*base%mod; b>>=1;
	}
	return ans;
}
void init(){ }
int n,m,k;
char s[205][2005];

map<string, pair<int,int> >mp;
void procedure(){
	n=read(), m=read(), k=read();
	for(int i=1;i<=n;i++){
		scanf("%s", s[i]+1);
	}	

	for(int i=1;i<=n;i++){
		for(int j=1;j<=m;j++){
			string S = "";
			for(int x=1+(j-1)*k;x<=j*k;x++) S += s[i][x];
			if(mp.count(S)){
				mp[S] = mkp(-1, -1);
			}else mp[S] = mkp(i, j);
		}
	}
	for(auto p: mp)
		if(p.se.se > 0){
			printf("%d %d\n", p.se.fi, p.se.se);
		}
}
int main(){
	#ifdef LOCAL
		assert(freopen("input.txt","r",stdin));
		assert(freopen("output.txt","w",stdout));
	#endif
	ll T=1;
	init();
	while(T--) procedure();
	return 0;
}