#include <iostream>

class Result {
public:
    int val;
    Result(int64_t v)
    {
        val = v;
    }

    int64_t ret()
    {
        return val;
    }
};

void bar(int64_t a, int64_t b, uint32_t k)
{
    if (k == 0) {
        throw Result(a+b);
    } else if (k > 0 && b == 1) {
        throw Result(a);
    } else if (k > 0 && b > 1) {
        try {
            bar(a, b - 1, k);
        } catch (Result t){
            try {
                bar(a, t.ret(), k - 1);
            } catch (Result t) {
                throw t;
            }
        }
    }
}

int main()
{
    int64_t a, b;
    uint32_t k;

    while (std::cin>>a>>b>>k) {
        try {
            bar(a, b, k);
        } catch(Result t) {
            std::cout<<t.ret()<<std::endl;
        }
    }
}