Visiting Cities

You want to travel from Syrjälä to Lehmälä by plane using a minimum-price route. Which cities will you certainly visit? Input The first input line contains two integers n and m: the number of cities and the number of flights. The cities are numbered 1,2,\ldots,n. City 1 is Syrjälä, and city n is Lehmälä. After this, there are m lines describing the flights. Each line has three integers a, b, an