#include <bits/stdc++.h>
using namespace std;
const int N=200010;
map<long long,int> mp;
int fa[N],d[N];
long long a,q,l[N],r[N],b[N],t=0,tot=0;
char s[N][11];
void get(int x) { if (!mp[x]) mp[x]=++t;}
int find(int x) 
{ 
    if (fa[x]==x) return x;
    int cnt=fa[x];
    fa[x]=find(fa[x]);
    d[x]=d[x]&d[cnt];
    return fa[x];
}
int main() {
    freopen("parity.in","r",stdin);
    freopen("parity.out","w",stdout);
    memset(d,-1,sizeof(d));
    for (int i=1;i<N-10;i++) fa[i]=i;
    cin>>a>>q;
    for (int i=1;i<=q;i++) scanf("%lld%lld%s",&l[i],&r[i],s[i]),b[++tot]=l[i]-1,b[++tot]=r[i]; 
    sort(b+1,b+tot+1);
    for (int i=1;i<=tot;i++) get(b[i]);
    for (int i=1;i<=q;i++)
    {
        if (s[i][0]=='e')
        {
            int x=mp[l[i]-1],y=mp[r[i]];
            int fx=find(x),fy=find(y);
            if (fx==fy && (d[x]^d[y]))
            {
                printf("%d",i-1);
                return 0;
            }
            fa[fx]=fy,d[fx]=(d[fy]^0);
        }
        else
        {
            int x=mp[l[i]-1],y=mp[r[i]];
            int fx=find(x),fy=find(y);
            if (fx==fy && !(d[x]^d[y]))
            {
                printf("%d",i-1);
                return 0;
            }
            fa[fx]=fy,d[fx]=(d[fy]^1);
        }
    }
    cout<<q;
}