#include<cstdio>
#include<algorithm>
using namespace std;
int fa[10010];
bool rel[10010];
int findroot(int x){
	if(x==fa[x]){
		return x;
	}
	int Fa=findroot(fa[x]);
	if(rel[x]==0 && rel[fa[x]]==0){
		rel[x]=0;
	}
	else if(rel[x]==0 && rel[fa[x]]==1){
		rel[x]=1;
	}
	else if(rel[x]==1 && rel[fa[x]]==0){
		rel[x]=1;
	}
	else if(rel[x]==1 && rel[fa[x]]==1){
		rel[x]=0;
	}
	return fa[x]=Fa;
}
struct Data{
	int v,p;
}t[10010];
bool cmp(const Data &a,const Data &b){
	return a.v<b.v;
}
int n,m,a[10010];
char op[5010][7];
int main(){
//	freopen("vijos1112.in","r",stdin);
	int e=0;
	scanf("%d%d",&n,&m);
	for(int i=1;i<=m;++i){
		scanf("%d%d%s",&t[(i<<1)-1].v,&t[i<<1].v,op[i]);
		--t[(i<<1)-1].v;
		t[(i<<1)-1].p=(i<<1)-1;
		t[i<<1].p=(i<<1);
	}
	sort(t+1,t+(m<<1|1),cmp);
	a[t[1].p]=++e;
	for(int i=2;i<=(m<<1);++i){
		if(t[i].v!=t[i-1].v){
			++e;
		}
		a[t[i].p]=e;
	}
	for(int i=1;i<=e;++i){
		fa[i]=i;
	}
	for(int i=1;i<=m;++i){
		int x=a[(i<<1)-1],y=a[i<<1];
		int f1=findroot(x),f2=findroot(y);
		if(f1==f2){
			if(op[i][0]==‘o‘){
				if(rel[x]==rel[y]){
					printf("%d\n",i-1);
					return 0;
				}
			}
			else{
				if(rel[x]!=rel[y]){
					printf("%d\n",i-1);
					return 0;
				}
			}
		}
		else{
			fa[f1]=f2;
			if(op[i][0]==‘o‘){
				if(rel[x]==0 && rel[y]==0){
					rel[f1]=1;
				}
				else if(rel[x]==0 && rel[y]==1){
					rel[f1]=0;
				}
				else if(rel[x]==1 && rel[y]==0){
					rel[f1]=0;
				}
				else if(rel[x]==1 && rel[y]==1){
					rel[f1]=1;
				}
			}
			else{
				if(rel[x]==0 && rel[y]==0){
					rel[f1]=0;
				}
				else if(rel[x]==0 && rel[y]==1){
					rel[f1]=1;
				}
				else if(rel[x]==1 && rel[y]==0){
					rel[f1]=1;
				}
				else if(rel[x]==1 && rel[y]==1){
					rel[f1]=0;
				}
			}
		}
	}
	printf("%d\n",m);
	return 0;
}