#include <stdio.h>
#include <string>
#include <cstring>
#include <stdlib.h>
#include <math.h>
#include <algorithm>
#include <vector>
#include <set>
#include <map>
#include <queue>
#include <stack>
#include <list>
#include <iterator>
#include <assert.h>
#pragma warning(disable:4996) 
 
typedef long long ll;
#define MIN(a, b) ((a)>(b)? (b): (a))
#define MAX(a, b) ((a)<(b)? (b): (a))
#define LINF 9223300000000000000
#define INF 2140000000
const long long MOD = 1000000007;
using namespace std;


ll mpow(ll x, ll n){ //x^n(mod M)
    ll ans = 1;
    while(n != 0){
        if(n&1) ans = ans*x % MOD;
        x = x*x % MOD;
        n = n >> 1;
    }
    return ans;
}

ll minv(ll x){
    return mpow( x, MOD-2 );
}

void mtxprd( int p, int q, int r, const ll* A, const ll* B, ll* C )
{
    int i, j, k;
    for(i=0; i<p; i++) {
        for(k=0; k<r; k++) {
            C[i*r+k] = 0;
            for(j=0; j<q; j++) {
                C[i*r+k] = (C[i*r+k] + A[i*q+j] * B[j*r+k])%MOD;
            }
        }
    } 
    return;
}
 
void mtxuni(int dim, ll* mtx){
    int i,j;
    for(i=0; i<dim; i++) {
        for(j=0; j<dim; j++) {
            mtx[i*dim+j]=(i==j? 1: 0);
        }
    }
    return;
}
 
void mtxcpy(int dim, const ll* mtx, ll* mtx2){
    int i,j;
    for(i=0; i<dim; i++) {
        for(j=0; j<dim; j++) {
            mtx2[i*dim+j]=mtx[i*dim+j];
        }
    }
    return;
}
 
void mtxpow(int dim, const ll* mtx, ll n, ll* mtx2){ //x^n(mod M)
    vector<ll> mtx0(dim*dim);
    vector<ll> mtxtmp(dim*dim);
    mtxcpy( dim, mtx, &mtx0[0] );
    mtxuni( dim, mtx2 );
    while(n != 0){        
        if(n&1) {
            mtxprd( dim, dim, dim, mtx2, &mtx0[0], &mtxtmp[0] );
            mtxcpy( dim, &mtxtmp[0], mtx2 );
        }
        mtxprd( dim, dim, dim, &mtx0[0], &mtx0[0], &mtxtmp[0] );
        mtxcpy( dim, &mtxtmp[0], &mtx0[0] );
        n = n >> 1;
    }
    return;
}


int main(int argc, char* argv[])
{
    int a,b,n;
    scanf("%d%d%d", &a, &b, &n);

    ll A[2*2] = {a, b, 1, 0};
    ll B[2*2];
    mtxpow( 2, A, n, B); 
    ll x0[2]={1,0};
    ll x1[2];
    mtxprd( 2, 2, 1, B, x0, x1 );
    printf("%lld\n", x1[1]);


    return 0;
}