#include <cstdio>
namespace solve0 {
	struct Matrix {
		int matrix[2][2];
		void init(int a,int b,int c,int d) {
			matrix[0][0]=a;matrix[0][1]=b;
			matrix[1][0]=c;matrix[1][1]=d;
		}
	};
	void mul(Matrix &a,const Matrix &b) {
		Matrix ans;
		for(int i=0;i<2;++i) {
			for(int j=0;j<2;++j) {
				ans.matrix[i][j]=0;
				for(int k=0;k<2;++k) {
					ans.matrix[i][j]=(ans.matrix[i][j]+a.matrix[i][k]*b.matrix[k][j])%7;
				}
			}
		}
		a=ans;
	}
	Matrix calc(const Matrix &x,int n) {
		if(n==1) {
			return x;
		}
		Matrix result=calc(x,n/2);
		mul(result,result);
		if(n%2) {
			mul(result,x);
		}
		return result;
	}
	int solve(int a,int b,int n) {
		if(n==1||n==2) return 1;
		Matrix x;
		x.init(a,b,1,0);
		Matrix y;
		y.init(1,0,1,0);
		x=calc(x,n-2);
		mul(x,y);
		return x.matrix[0][0];
	}
}
int main() {
	freopen("number1.in","r",stdin);
	freopen("number1.out","w",stdout);
	int a,b,n;
	while(scanf("%d%d%d",&a,&b,&n)==3) {
		printf("%d\n",solve0::solve(a,b,n));
	}
	fclose(stdin);
	fclose(stdout);
	return 0;
}