#include<stdio.h>
#include<map>
using namespace std;
map<pair<int, int>, int>M;
char T[256];
int dx[4] = { 1,0,-1,0 };
int dy[4] = { 0,1,0,-1 };
int min(int a, int b) { if (a < b)return a; return b; }
int main() {
	T['N'] = 0, T['E'] = 1, T['S'] = 2, T['W'] = 3;
	int n;
	int ans = 1e9;
	scanf("%d", &n);
	int nowx = 0, nowy = 0, nowt = 1;
	M[{0, 0}] = nowt;
	for (int i = 0; i < n; i++) {
		char x; int t;
		scanf(" %c%d", &x, &t);
		for (int j = 0; j < t; j++) {
			nowx += dx[T[x]], nowy += dy[T[x]], nowt++;
			if (M[{nowx, nowy}])ans = min(ans, nowt - M[{nowx, nowy}]);
			M[{nowx, nowy}] = nowt;
		}
	}
	if (ans == 1e9)ans = -1;
	printf("%d", ans);
	return 0;
}

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NgpOIDEwCkUgMgpTIDMKVyA0ClMgNQpFIDg=

6
N 10
E 2
S 3
W 4
S 5
E 8