#include <bits/stdc++.h>

using namespace std;

int main()
{
    //freopen("mowing.in","r",stdin);
    //freopen("mowing.out","w",stdout);
    int n;
    cin>>n;
    pair<char,int> niza[n];
    for(int i=0; i<n; i++)
    {
        cin>>niza[i].first>>niza[i].second;
    }
    int x=350;
    int y=350;
    int vis[700][700];
    memset(vis,-1,sizeof(vis));
    vis[x][y]=0;
    int currstep=1;
    int MAX=0;
    for(int i=0; i<n; i++)
    {
        char direction=niza[i].first;
        int steps=niza[i].second;
        for(int q=0; q<steps; q++)
        {
            if(direction=='N')
            {
                y--;
                if(vis[x][y]!=-1)
                {
                    cout<<currstep-vis[x][y]<<endl;
                    return 0;
                }
                vis[x][y]=currstep;
                currstep++;
            }
            else if(direction=='S')
            {
                y++;
                if(vis[x][y]!=-1)
                {
                    cout<<currstep-vis[x][y]<<endl;
                    return 0;
                }
                vis[x][y]=currstep;
                currstep++;
            }
            else if(direction=='W')
            {
                x--;
                if(vis[x][y]!=-1)
                {
                    cout<<currstep-vis[x][y]<<endl;
                    return 0;
                }
                vis[x][y]=currstep;
                currstep++;
            }
            else
            {
                x++;
                if(vis[x][y]!=-1)
                {
                    cout<<currstep-vis[x][y]<<endl;
                    return 0;
                }
                vis[x][y]=currstep;
                currstep++;
            }
        }
    }
    cout<<-1<<endl;
    return 0;
}