rt

#include <bits/stdc++.h>
using namespace std;
bool judge(char s, char a[100][100], int i, int j, int n, int m) {
    if (s == 'v') {
        while (i <= n) {
            i++;
            if (a[i][j] == 'x') {
                return 0;
            }
        }
        return 1;
    }
    if (s == '>') {
        while (j <= m) {
            j++;
            if (a[i][j] == 'x') {
                return 0;
            }
        }
        return 1;
    }
    if (s == '^') {
        while (i >= n) {
            i--;
            if (a[i][j] == 'x') {
                return 0;
            }
        }
        return 1;
    }
    if (s == '<') {
        while (j >= m) {
            j--;
            if (a[i][j] == 'x') {
                return 0;
            }
        }
        return 1;
    }
}


int main() {
    char a[100][100], s;
    int n, m;

    cin >> n >> m >> s;
    for (int i = 0; i < n; i++) {
        for (int j = 0; j < m; j++) {
            cin >> a[i][j];
        }
    }
    for (int i = 0; i < n; i++) {
        for (int j = 0; j < m; j++) {
            if (a[i][j] == 'o') {
                if (!judge(s, a, i, j, n, m)) {
                    cout << "GG";
                    return 0;
                }
            }
        }
    }
    cout << "OK";
    return 0;
}