unsigned@n,@m;
int a[m],b[];
unsigned c[];
rd((a--,b--,c)(m));
unsigned@t[n];
wgraph<unsigned>g;
g.setEdge(n,m,a,b,c);
DijkstraHeap<unsigned>h;
h.walloc(n<<10,1);
h.change(0,0);
while(1){
	unsigned s=h.pop();
	unsigned u=s>>10;
	unsigned w=h.val[s];
	if(u==n-1){
		wt(w);
		exit(0);
	}
	w+=t[u];
	s=min(1023,(s&1023)+t[u]);
	rep(j,g.es[u]){
		h.change(g.edge[u][j]<<10|s,w+g.cost[u][j]/s);
	}
}