const maxp=10000; {最大结点数}var p,c,s,t:longint; {p,结点数;c,边数;s:起点;t:终点}　   a,b:array[1..maxp,0..maxp] of longint; {a[x,y]存x,y之间边的权;b[x,c]存与x相连的第c个边的另一个结点y}　   d:array[1..maxp] of integer; {队列}　   v:array[1..maxp] of boolean; {是否入队的标记}　   dist:array[1..maxp] of longint; {到起点的最短路}　   head,tail:longint; {队首/队尾指针}procedure init;var i,x,y,z:longint;begin  read(p,c);   for i := 1 to c do   begin     readln(x,y,z); {x,y:一条边的两个结点;z:这条边的权值}     inc(b[x,0]); b[x,b[x,0]] := y; a[x,y] := z; {b[x,0]：以x为一个结点的边的条数}     inc(b[y,0]); b[y,b[y,0]] := x; a[y,x] := z;   end;  readln(s,t); {读入起点与终点}end;procedure spfa(s:longint); {SPFA}var i,j,now,sum:longint;begin  fillchar(d,sizeof(d),0);  fillchar(v,sizeof(v),false);  for j := 1 to p do dist[ j ]:=maxlongint;  dist[s] := 0; v[s] := true; d[1] := s; {队列的初始状态,s为起点}  head := 1; tail := 1;  while head<=tail do {队列不空}    begin      now := d[head]; {取队首元素}      for i := 1 to b[now,0] do        if dist[b[now,i]]>dist[now]+a[now,b[now,i]] then          begin            dist[b[now,i]]:= dist[now]+a[now,b[now,i]]; {修改最短路}            if not v[b[now,i]] then {扩展结点入队}              begin                inc(tail);                d[tail] := b[now,i];                v[b[now,i]] := true;              end;          end;      v[now] := false; {释放结点}      inc(head); {出队}    end;end;procedure print;begin  writeln(dist[t]);end;begin  init;  spfa(s);  print;end.