def main():
    try:
        import pypyjit
        pypyjit.set_param('max_unroll_recursion=-1')
    except:
        pass
    try:
        import sys
        sys.setrecursionlimit(10**7)
    except:
        pass
    from math import sqrt,sin,cos,tan,ceil,radians,floor,gcd,exp,log,log10,log2,factorial,fsum
    from heapq import heapify, heappop, heappush
    from bisect import bisect_left, bisect_right
    from copy import deepcopy
    import copy
    import random
    from collections import deque,Counter,defaultdict
    from itertools import permutations,combinations
    from decimal import Decimal,ROUND_HALF_UP
    #tmp = Decimal(mid).quantize(Decimal('0'), rounding=ROUND_HALF_UP)
    from functools import lru_cache, reduce
    #@lru_cache(maxsize=None)
    from operator import add,sub,mul,xor,and_,or_,itemgetter
    INF = 10**18
    mod1 = 10**9+7
    mod2 = 998244353
    
    #DecimalならPython
    
    '''
    自明解は避ける
    
    '''
    
    def matmul(a, b, mod):
        m = len(a)
        l = len(a[0])
        n = len(b[0])
        ret = [[0] * n for _ in range(m)]
        for i in range(m):
            for j in range(n):
                e = 0
                for k in range(l):
                    e = (e + a[i][k] * b[k][j]) % mod
                ret[i][j] = e
        return ret
    
    
    def matpow(X, exp, mod):
        Y = [[int(i == j) for j in range(len(X))] for i in range(len(X))]
        while exp > 0:
            if exp & 1:
                Y = matmul(X, Y, mod)
            X = matmul(X, X, mod)
            exp >>= 1
        return Y
    
    a,b,n = map(int, input().split())
    
    A = [[a,b],[1,0]]
    
    B = matpow(A,n-1,mod1)
    
    print(B[0][0])
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
if __name__ == '__main__':
    main()