rt

#include<bits/stdc++.h>

using namespace std;

const int MAXN = 2e3 + 10;

int n, m, sx, sy, fx, fy, ans[MAXN][MAXN];
char c[MAXN][MAXN];
int dx[] = {-1, 1, 0, 0}, dy[] = {0, 0, -1, 1};
struct node {
    int x, y, step;
};
deque<node> q;
void Record(int x, int y, int step) {
    if(x < 1 || y < 1 || x > n || y > m || c[x][y] == '#' || ans[x][y] <= step) {
        return;
    }
    q.push_back({x, y, step});
    ans[x][y] = step;
}
void bfs(int x, int y) {
    fill(ans[0] + 1, ans[n] + m + 1, INT_MAX);
    Record(x, y, 0);
    while(!q.empty()) {
        node now = q.front();
        q.pop_front();
        for(int i = 0; i < 4; i++) {
            int nx = now.x + dx[i], ny = now.y + dy[i];
            Record(nx, ny, now.step + 1);
        }
    }
}

int main() {
    cin >> n >> m;
    for(int i = 1; i <= n; i++) {
        for(int j = 1; j <= m; j++) {
            cin >> c[i][j];
            if(c[i][j] == 'S') {
                sx = i, sy = j;
            }
            if(c[i][j] == 'G') {
                fx = i, fy = j;
            }
        }
    }
    for(int i = 1; i <= n; i++) {
        for(int j = 1; j <= m; j++) {
            if(c[i][j] == '^') {
                int x = i, y = j;
                c[x][y] = '.';
                for(; c[x][y] == '.' && x >= 1; x += -1) {
                    c[x][y] = '#';
                }
            }
            else if(c[i][j] == '<') {
                int x = i, y = j;
                c[x][y] = '.';
                for(; c[x][y] == '.' && y >= 1; y += -1) {
                    c[x][y] = '#';
                }
            }
            else if(c[i][j] == '>') {
                int x = i, y = j;
                c[x][y] = '.';  
                for(; c[x][y] == '.' && y <= m; y += 1) {
                    c[x][y] = '#';
                }
            }
            else if(c[i][j] == 'v') {
                int x = i, y = j;
                c[x][y] = '.';
                for(; c[x][y] == '.' && x <= n; x++) {
                    c[x][y] = '#';
                }
            }
        }
    }
    bfs(sx, sy);
    cout << (ans[fx][fy] == INT_MAX ? -1 : ans[fx][fy]);
    return 0;
}