今天晴天

type pt=array[0..100000] of longint;
var
  p,d,rank,node:pt;
  x,y,t1,t2,t,n,m,i:longint;
  s:string;

procedure union(x,y:longint);
begin
  if rank[x]>rank[y] then
    p[y]:=x else begin
      p[x]:=y;
      if rank[x]=rank[y] then inc(rank[y]);
    end;
end;

function findset(x:longint):longint;
begin
  if p[x]<>x then p[x]:=findset(p[x]);
  exit(p[x]);
end;

begin
  readln(n);
  readln(m);
  node[1]:=0;
  for i:=1 to 2*m do
    d[i]:=-1;
  for i:=1 to m do begin
    read(x,y);
 
    t1:=1; dec(x);
    while (t1<=t)and(node[t1]<>x) do inc(t1);
    if t1>t then begin
      inc(t);   node[t]:=x;
      p[t]:=t;  rank[t]:=0;
    end;
 
    t2:=1;
    while (t2<=t)and(node[t2]<>y) do inc(t2);
    if t2>t then begin
      inc(t);  node[t]:=y;
      p[t]:=t; rank[t]:=0;
    end;

    readln(s);
    if s[length(s)]='n' then
     if (findset(d[t1])=findset(t2))or(findset(t1)=findset(d[t2])) then begin
       writeln(i-1);
       halt;
     end else begin
       if findset(t1)<>findset(t2) then
       union(findset(t1),findset(t2));
       if findset(d[t1])<>findset(d[t2]) then
       union(findset(d[t1]),findset(d[t2]));
     end;
 
   if s[length(s)]='d' then begin
     if d[t1]=-1 then d[t1]:=t2;
     if d[t2]=-1 then d[t2]:=t1;
     if (findset(t1)=findset(t2))or(findset(d[t1])=findset(d[t2])) then begin
       writeln(i-1);
       halt;
     end else
       if findset(d[t1])<>findset(t2) then union(findset(d[t1]),findset(t2));
     if findset(t1)<>findset(d[t2]) then union(findset(t1),findset(d[t2]));
   end;

  end;
  writeln(m);
end.