static void Main()
{
var h = Read();
var n = h[0];
var es = Array.ConvertAll(new bool[h[1]], _ => Read());
var mf = new MinCostFlow(n);
mf.AddEdges(es);
var r = mf.GetMinCost(0, n - 1, h[2]);
Console.WriteLine(r == long.MaxValue ? -1 : r);
}
