require 'matrix'

a,b,n=gets.split.map(&:to_i)
$mod = 1000000007
$memo={}
def rui(m,x)
    m.map!{|e|e%$mod}

    return $memo[x] if($memo.key?(x))
    # p m
    if x==1
        m
    else
        return $memo[x] = if x.even?
            rui(m,x/2)*rui(m,x/2).map!{|e|e%$mod}
        else
            rui(m,x-1)*m.map!{|e|e%$mod}
        end
    end
end

ma = Matrix[[a, b], [1, 0]]

p (rui(ma,n)*Matrix[[1],[0]])[1,0]%$mod.ceil