#include <iostream>
#include <cstdio>
#include <deque>
#include <map>
#include <string>
#include <cstring>
#include <cstdlib>
#include <algorithm>
#include <functional>
using namespace std;
const int maxn=20002;
int Hlen=6000;
int father[maxn];
int flag[maxn];
int getfather(int x)
{
    int tmp=father[x];
    if(x==father[x])
        return x;
        else
        {
            father[x]=getfather(father[x]);
            return father[x];
        }
}
void Union(int x,int y)
{
    int fx=getfather(x);
    int fy=getfather(y);
    if(fx!=fy)
      father[fy]=fx;
}
void init()
{
    for(int i=0;i<maxn;i++)
        father[i]=i;
}
int mp(int x)
{
    int ax=x%Hlen;
    if(flag[ax]!=-1&&flag[ax]!=x)
        ax=(ax+1)%Hlen;
    flag[ax]=x;
    return ax;
}
int main()
{
    int len,N,i;
    int level=10000;

    while(1)
    {
    scanf("%d",&len);
    if(len==-1)
        break;
    scanf("%d",&N);

    init();
    memset(flag,-1,sizeof (flag));
    for(i=0;i<N;i++)
    {
        int a,b;
        char str[10];
        scanf("%d%d%s",&a,&b,str);
        a=mp(a-1);
        b=mp(b);
        if(str[0]=='e')
        {
            if(getfather(a)==getfather(b+level))
                break;
            Union(a,b);
            Union(a+level,b+level);
        }
        else
        {
            if(getfather(a)==getfather(b))
                break;
            Union(a,b+level);
            Union(a+level,b);
        }
    }
    char str1[100];

    int m=i;
    for(i;i<N;i++)
        gets(str1);
    printf("%d\n",m);

    }
    system("pause");
    return 0;
}