#include <bits/stdc++.h>
#define rep(i,n) for(int i = 0; i < (n); ++i)
#define srep(i,s,t) for (int i = s; i < t; ++i)
#define drep(i,n) for(int i = (n)-1; i >= 0; --i)
using namespace std;
typedef long long int ll;
typedef pair<int,int> P;
#define yn {puts("YES");}else{puts("NO");}
#define MAX_N 200005

int main() {
    int n, m;
    cin >> n >> m;
    int flag = 0;
    rep(i,n){
        string s;
        cin >> s;
        rep(j,m - 3){
            if(s[j] == 'L' && s[j+1] == 'O' && s[j+2] == 'V' && s[j+3] == 'E'){
                flag = 1;
            }
        }
    }

    if(flag)yn;
    return 0;
}