require 'matrix'

a,b,n=gets.split.map(&:to_i)
mod = 1e9+7
def rui(m,x)
    if x==1
        m
    else
        if x.even?
            rui(m,x/2)*rui(m,x/2)
        else
            rui(m,x-1)*m
        end
    end
end

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

p (rui(ma,n)*Matrix[[1],[0]])[1,0]%mod.ceil
# .tap{|e|p e[0,1]}