#include <map>
#include <vector>
#include <climits>
using namespace std;

int main() {
    int N;
    cin >> N;

    map<pair<int,int>, vector<int>> visits;

    int x = 0, y = 0, t = 0;
    visits[{x, y}].push_back(t);

    for (int i = 0; i < N; i++) {
        char dir;
        int steps;
        cin >> dir >> steps;
        for (int s = 0; s < steps; s++) {
            if (dir == 'N') y++;
            else if (dir == 'E') x++;
            else if (dir == 'S') y--;
            else x--;
            t++;
            visits[{x, y}].push_back(t);
        }
    }

    int ans = INT_MAX;
    for (auto& p : visits) {
        auto& times = p.second;
        for (int i = 1; i < (int)times.size(); i++) {
            ans = min(ans, times[i] - times[i - 1]);
        }
    }

    if (ans == INT_MAX) cout << -1 << endl;
    else cout << ans << endl;

    return 0;
}