#include<bits/stdc++.h>
using namespace std;
inline int re()
{
    int f=1,num=0;
   char c=getchar();
    while(c<'0'||c>'9'){if(c=='-') f=-1;c=getchar();}
    while(c>='0'&&c<='9') num=num*10+c-'0',c=getchar();
    return num*f;
}
const int N=5010;
vector<int> ys;
int n,m,q;
int fa[4*N],sz[4*N];
int get(int x)
{
    if(fa[x]==x) return x;
    return fa[x]=get(fa[x]);
}
void merge(int x,int y)
{
    x=get(x);y=get(y);
    if(x==y) return;
    if(sz[x]>sz[y]) swap(x,y);
    fa[x]=y;sz[y]+=sz[x];
    return;
}
char c[10];
struct query
{
    int l,r,ans;
}qs[N];
int cha(int x)
{
    int l=0,r=m-1,mid;
    while(l<r)
    {
        mid=(l+r)/2;
        if(ys[mid]>=x) r=mid;
        else l=mid+1;
    }
    return l+1;
}
int main()
{
    freopen("parity.in","r",stdin);
    freopen("parity.out","w",stdout);
    n=re();q=re();
    for(int i=1;i<=q;i++)
    {
        qs[i].l=re();qs[i].r=re();
        ys.push_back(qs[i].l-1);ys.push_back(qs[i].r);
        scanf("%s",c);
        if(c[0]=='e') qs[i].ans=0;
        else qs[i].ans=1;
    }
    sort(ys.begin(),ys.end());
    ys.erase(unique(ys.begin(),ys.end()),ys.end());
    m=ys.size();
    for(int i=1;i<=2*m;i++) fa[i]=i,sz[i]=0;
    int x,y;
    for(int i=1;i<=q;i++)
    {
        x=cha(qs[i].l-1),y=cha(qs[i].r);
        if(qs[i].ans==0) merge(x,y),merge(x+m,y+m);
        else merge(x,y+m),merge(x+m,y);
        if(get(x)==get(x+m)||get(y)==get(y+m))
        {
            printf("%d",i-1);
            return 0;
        }
    }
    printf("%d",q);
    return 0;
}