{"trustable":true,"prependHtml":"\u003cstyle type\u003d\"text/css\"\u003e\n h1 { font-size: 1.2em; }\n\u003c/style\u003e\n","sections":[{"title":"","value":{"format":"HTML","content":"\n\u003cdiv class\u003d\"md\"\u003e\u003cp\u003eYou want to travel from Syrjälä to Lehmälä by plane using a minimum-price route. Which cities will you certainly visit?\u003c/p\u003e\n\u003ch1 id\u003d\"input\"\u003eInput\u003c/h1\u003e\n\u003cp\u003eThe first input line contains two integers \u003cspan class\u003d\"math inline\"\u003e$ n $\u003c/span\u003e and \u003cspan class\u003d\"math inline\"\u003e$ m $\u003c/span\u003e: the number of cities and the number of flights. The cities are numbered \u003cspan class\u003d\"math inline\"\u003e$ 1,2,\\ldots,n $\u003c/span\u003e. City 1 is Syrjälä, and city \u003cspan class\u003d\"math inline\"\u003e$ n $\u003c/span\u003e is Lehmälä.\u003c/p\u003e\n\u003cp\u003eAfter this, there are \u003cspan class\u003d\"math inline\"\u003e$ m $\u003c/span\u003e lines describing the flights. Each line has three integers \u003cspan class\u003d\"math inline\"\u003e$ a $\u003c/span\u003e, \u003cspan class\u003d\"math inline\"\u003e$ b $\u003c/span\u003e, and \u003cspan class\u003d\"math inline\"\u003e$ c $\u003c/span\u003e: there is a flight from city \u003cspan class\u003d\"math inline\"\u003e$ a $\u003c/span\u003e to city \u003cspan class\u003d\"math inline\"\u003e$ b $\u003c/span\u003e with price \u003cspan class\u003d\"math inline\"\u003e$ c $\u003c/span\u003e. All flights are one-way flights.\u003c/p\u003e\n\u003cp\u003eYou may assume that there is a route from Syrjälä to Lehmälä.\u003c/p\u003e\n\u003ch1 id\u003d\"output\"\u003eOutput\u003c/h1\u003e\n\u003cp\u003eFirst print an integer \u003cspan class\u003d\"math inline\"\u003e$ k $\u003c/span\u003e: the number of cities that are certainly in the route. After this, print the \u003cspan class\u003d\"math inline\"\u003e$ k $\u003c/span\u003e cities sorted in increasing order.\u003c/p\u003e\n\u003ch1 id\u003d\"constraints\"\u003eConstraints\u003c/h1\u003e\n\u003cul\u003e\n\u003cli\u003e\u003cspan class\u003d\"math inline\"\u003e$ 1 \\le n \\le 10^5 $\u003c/span\u003e\u003c/li\u003e\n\u003cli\u003e\u003cspan class\u003d\"math inline\"\u003e$ 1 \\le m \\le 2 \\cdot 10^5 $\u003c/span\u003e\u003c/li\u003e\n\u003cli\u003e\u003cspan class\u003d\"math inline\"\u003e$ 1 \\le a,b \\le n $\u003c/span\u003e\u003c/li\u003e\n\u003cli\u003e\u003cspan class\u003d\"math inline\"\u003e$ 1 \\le c \\le 10^9 $\u003c/span\u003e\u003c/li\u003e\n\u003c/ul\u003e\n\u003ch1 id\u003d\"example\"\u003eExample\u003c/h1\u003e\n\u003ctable class\u003d\"vjudge_sample\"\u003e\n\u003cthead\u003e\n \u003ctr\u003e\n \u003cth\u003eInput\u003c/th\u003e\n \u003cth\u003eOutput\u003c/th\u003e\n \u003c/tr\u003e\n\u003c/thead\u003e\n\u003ctbody\u003e\n \u003ctr\u003e\n \u003ctd\u003e\u003cpre\u003e5 6\n1 2 3\n1 3 4\n2 3 1\n2 4 5\n3 4 1\n4 5 8\n\u003c/pre\u003e\u003c/td\u003e\n \u003ctd\u003e\u003cpre\u003e4\n1 3 4 5\n\u003c/pre\u003e\u003c/td\u003e\n \u003c/tr\u003e\n\u003c/tbody\u003e\n\u003c/table\u003e\n\u003c/div\u003e "}}]}