#include <cmath>
#include <cstdio>
#include <vector>
#include <iostream>
#include <algorithm>
using namespace std;


int main() {
    int a,b;
    long t, cells=1;
    scanf("%d %d %ld", &a, &b, &t);
    for(long i=0; i<t; i++){
        cells = (a*cells + b*cells)/2;
    }
    cells=cells%(10^9 + 7);
    printf("%ld", cells);
    return 0;
}