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

#define int long long
typedef pair<int,int>pint;
typedef vector<int>vint;
typedef vector<pint>vpint;
#define pb push_back
#define mp make_pair
#define fi first
#define se second
#define all(v) (v).begin(),(v).end()
#define rep(i,n) for(int i=0;i<(n);i++)
#define reps(i,f,n) for(int i=(f);i<(n);i++)
#define each(it,v) for(__typeof((v).begin()) it=(v).begin();it!=(v).end();it++)
template<class T,class U>inline void chmin(T &t,U f){if(t>f)t=f;}
template<class T,class U>inline void chmax(T &t,U f){if(t<f)t=f;}

int H,W,N;
vector<string>fld;

void down(){
    rep(j,W){
        int t=0;
        rep(i,H){
            if(isalpha(fld[i][j])){
                fld[t++][j]=fld[i][j];
            }
        }
        reps(i,t,H)fld[i][j]='.';
    }
}
bool is_del[33][33];

bool del(){
    memset(is_del,0,sizeof(is_del));
    bool sc=false;
    rep(i,H){
        rep(j,W-N+1){
            if(fld[i][j]=='.')continue;
            bool ok=true;
            rep(k,N)if(fld[i][j]!=fld[i][j+k])ok=false;
            if(ok)rep(k,N)is_del[i][j+k]=true;
            sc|=ok;
        }
    }

    rep(j,W){
        rep(i,H-N+1){
            if(fld[i][j]=='.')continue;
            bool ok=true;
            rep(k,N)if(fld[i][j]!=fld[i+k][j])ok=false;
            if(ok)rep(k,N)is_del[i+k][j]=true;
            sc|=ok;
        }
    }
    rep(i,H)rep(j,W)if(is_del[i][j])fld[i][j]='.';
    return sc;
}

bool check(){
    down();
    while(del())down();
    rep(i,H)rep(j,W)if(fld[i][j]!='.')return false;
    return true;
}

signed main(){
    cin>>H>>W>>N;
    vector<string>in;
    in.resize(H);
    rep(i,H)cin>>in[H-1-i];

    rep(i,H)rep(j,W-1){
        fld=in;
        swap(fld[i][j],fld[i][j+1]);
        if(check()){
            cout<<"YES"<<endl;
            return 0;
        }
    }
    cout<<"NO"<<endl;
    return 0;
}