#include <iostream>

 #include <cstdio>

 #include <vector>

 #include <algorithm>

 #include <map>

 #include <cstring>

 #include <cmath>

 using namespace std;

 const int maxn=;

 struct query{

     int l,r;

     int oe;

 }q[maxn];

 map<int,int> lists;

 int v[maxn],fa[maxn];

 int finds(int t){

     if(fa[t]==-)

         return t;

     int tmp=finds(fa[t]);

     v[t]^=v[fa[t]];

     return fa[t]=tmp;

 }

 int main(){

 //    freopen("in.txt","r",stdin);

 //    freopen("out.txt","w",stdout);

     int vals[maxn<<];

     char ooe[];

     int ques,len;

     memset(fa,-,sizeof(fa));

     memset(v,,sizeof(v));

     scanf("%d",&len);

     scanf("%d",&ques);

     int j=;

     for(int i=;i<=ques;i++){

         scanf("%d%d%s",&q[i].l,&q[i].r,ooe);

         q[i].l-=;

         if(ooe[]=='e')     q[i].oe=;

         else    q[i].oe=;

         vals[j]=q[i].l;     j++;

         vals[j]=q[i].r;     j++;

     }

     sort(vals+,vals+j);

     int m=unique(vals+,vals+j)-vals-;

     for(int i=;i<=m;i++){

         lists[vals[i]]=i;

     }

     int ending=;

     for(int i=;i<=ques;i++){

         int t1=finds(lists[q[i].l]),t2=finds(lists[q[i].r]);

         int vl=v[lists[q[i].l]],vr=v[lists[q[i].r]];

         if(t1==t2){

             if(vr^vl!=q[i].oe){

                 printf("%d\n",i-);

                 ending=;

                 break;

             }

         }

         else{

             fa[t2]=t1;

             v[t2]=q[i].oe^vl^vr;

         }

     }

     if(!ending) printf("%d\n",ques);

     return ;

 }