def f():
    var x, y, m, n

    while x + 3 <= n:
        if y < m:
            prob(1,1):
                y = y + 1
            else:
                y = y + 0
        else:
            prob(1,3):
                x = x + 0
            else:
                prob(1,2):
                  x = x + 1
                else:
                    prob(1,1):
                        x = x + 2
                    else:
                        x = x + 3
        tick 1