#include <cstdio>
#include <cstring>
#include <cstdarg>
#include <list>
#include <queue>
#include <vector>
#include <algorithm>
#include <deque>
using namespace std;
struct matrix{
  int a[3][3];
};
void matrix_puts(matrix &x, int m, int n){
  for(int i = 1; i <= m; i++){
    for(int j = 1; j <= n; j++){
      printf("%d ", x.a[i][j]);
    }
    putchar('\n');
  }
}
void matrix_mul(matrix A, matrix B, matrix &C, int m, int n, int p){
  for(int i = 1; i <= m; i++)
    for(int j = 1; j <= p; j++){
      C.a[i][j] = 0;
      for(int k = 1; k <= n; k++)
        C.a[i][j] = (C.a[i][j]+A.a[i][k]*B.a[k][j])%7;
    }
}
matrix matrix_pow(matrix a, long long x){
  matrix ans;
  ans.a[1][1] = ans.a[2][2] = 1;
  ans.a[1][2] = ans.a[2][1] = 0;
  matrix tmp;
  for(; x; x >>= 1){
    if(x&1){
      matrix_mul(ans, a, tmp, 2, 2, 2);
      ans = tmp;
    }
    matrix_mul(a, a, tmp, 2, 2, 2);
    a = tmp;
  }
  return ans;
}
int main(){
  freopen("number1.in", "r", stdin);
  freopen("number1.out", "w", stdout);
  int a, b;
  long long n;
  while(~scanf("%d %d %lld", &a, &b, &n)){
    if(n < 2){
      puts("1");
      continue;
    }
    matrix x;
    x.a[1][1] = a; x.a[2][1] = b;
    x.a[1][2] = 1; x.a[2][2] = 0;
    x = matrix_pow(x, n-2);
    matrix s;
    s.a[1][1] = s.a[1][2] = 1;
    matrix r;
    matrix_mul(s, x, r, 1, 2, 2);
    printf("%d\n", r.a[1][1]);
  }
  return 0;
}