/*
Project: Ural
Author: Ai.Freedom
Title: Parity
Date: 20020214
Time: 1809
Tested Problem: Ural 1003
Status: 1/2
Remark: 终于在情人节AC.. 并查集, 这里用到的方法很巧妙.
*/
#include <iostream>
#include <string>
using namespace std;
const int maxn = 65521+1000, bigprime = 65521;
int data[maxn], f[maxn], n, m;
bool r[maxn];
unsigned int hash(unsigned int num)
{
	unsigned int d;
	d = num % bigprime;
	while (data[d] != -1 && data[d] != num) d = (d + 1) % bigprime;
	data[d] = num; return d;
}

void pathcomp(unsigned int x)
{
	unsigned int s, t;
	bool a, b;
	a = false; s = x;
	while (f[s] != s) {a ^= r[s], s = f[s];}
	while (x != s)
	{
		b = a ^ r[x], r[x] = a, a = b;
		t = x, x = f[x], f[t] = s;
	}
}
void init()
{
	memset(data, -1, sizeof(data)), memset(r, false, sizeof(r));
	for (int i=0; i<maxn; i++) f[i] = i;
	cin >> n;
}
void calc()
{
	int i;
	unsigned int a, b, x, y;
	string str;
	bool t;
	for (i=0; i<n; i++)
	{
		cin >> a >> b >> str;
		a--;
		x = hash(a), y = hash(b);
		t = (str == "odd");
		pathcomp(x), pathcomp(y);
		if (f[x] != f[y])
		{
			r[f[x]] = (t ^ r[x] ^ r[y]);
			f[f[x]] = f[y];
		} 
		else
		{
			if ((r[x] ^ r[y]) != t)
			{
				cout << i << endl;
				for (int j=i+1; j<n; j++) cin >> a >> b >> str;
				return;
			}
		}
	}
	cout << n << endl;
}

int main()
{
#ifndef ONLINE_JUDGE
	freopen("1003.in", "rt", stdin);
	freopen("1003.out", "wt", stdout);
#endif
	cin >> n;
	while (n != -1)
	{
		init();
		calc();
		cin >> n;
	}
	return 0;
}