#include <cstdio>
#include <cstring>
#include <cstdlib>
#include <algorithm>
#define N 200000
using namespace std;
int rank[N],fa[N],n,cnt,m,bh;
bool jo[N];
struct P
{
	int id,q,h;
}p[N];
inline bool cmp_q(const P &a,const P &b)
{
	return a.q<b.q;
}
inline bool cmp_id(const P &a,const P &b)
{
	if(a.id!=b.id) return a.id<b.id;
	else return a.h<b.h;
}
int findfa(int x)
{
	if(fa[x]!=x)
	{
		findfa(fa[x]);
		rank[x]+=rank[fa[x]];
		fa[x]=findfa(fa[x]);
	}
	return fa[x];
}
void read()
{
	cnt=0;char str[5];
	scanf("%d",&m);
	for(int i=1;i<=m;i++)
	{
		scanf("%d",&p[++cnt].q);
		p[cnt].q--;
		p[cnt].id=i;
		scanf("%d",&p[++cnt].q);
		p[cnt].id=i;
		scanf("%s",str);
		if(str[0]=='o') jo[i]=1;//奇数 
		else jo[i]=0;//偶数 
	}
}
void lsh()
{
	sort(p+1,p+1+cnt,cmp_q);
	p[1].h=1;
	bh=1;
	for(int i=2;i<=cnt;i++)
	{
		if(p[i].q==p[i-1].q) p[i].h=bh;
		else p[i].h=++bh;
	}
	sort(p+1,p+1+cnt,cmp_id);
}
void go()
{
	for(int i=0;i<N;i++) fa[i]=i,rank[i]=0;
	for(int i=1;i<=cnt;i+=2)
	{
		if(findfa(p[i].h)!=findfa(p[i+1].h))
		{
			if(((rank[p[i].h]+rank[p[i+1].h])&1)==jo[p[i].id])
			{
				rank[fa[p[i+1].h]]=0;
				fa[fa[p[i+1].h]]=fa[p[i].h];
			}
			else
			{
				rank[fa[p[i+1].h]]=1;
				fa[fa[p[i+1].h]]=fa[p[i].h];	
			}
		}
		else
		{
			if(((rank[p[i].h]+rank[p[i+1].h])&1)!=jo[p[i].id])
			{
				printf("%d\n",p[i].id-1);
				return;
			}
		}
	}
	printf("%d\n",m);
}
int main()
{
	scanf("%d",&n);
	read();
	lsh();
	go();
	system("pause");
	return 0;
}