using namespace std;
char mapp[114][514];
bool ass=0;
int m,n;
void dfs(int x,int y,char z){
	if(mapp[x][y]=='x'){
		cout<<"GG";
		return;
	}
	else if(x>=m||y>=n||x<0||y<0){
		cout<<"OK";
		return ;
	}
	if(z=='^'){
		dfs(x,y-1,z);
	}if(z=='<'){
		dfs(x-1,y,z);
	}if(z=='>'){
		dfs(x+1,y,z);
	}if(z=='v'){
		dfs(x,y+1,z);
	}
}
int main(){
	int a,b;
	char s;
	cin>>m>>n>>s;
	for(int i=0;i<n;i++){
		for(int j=0;j<m;j++){
			cin>>mapp[j][i];
			if(mapp[j][i]=='o'){
			a=j;
			b=i;
			ass=1;
			}
		}
	}
	if(ass)
	dfs(a,b,s);
	else
	cout<<"OK";
	return 0;
}