/*
TASK:String
LANG:C++
*/
#include<iostream>
#include<string>
#include<algorithm>
using namespace std;

string s,t;
string m,m1;
int p;

int main()
{
	cin>>s;
	cin>>t;
	cin>>p;
	int i,j,cnt=0;
	for(i=0;i<=p;i++)
	{ 
		 m.clear();
		 m.resize(p);
		 for(j=0;j<i;j++)
		 m[j]=t[0];
		 for(j=i;j<p;j++)
		 m[j]=t[1];
		 m1=m;
		 if(!(m.find(s)<=p))cnt++;
		 next_permutation(m.begin(),m.end());
		 while(m1!=m)
		 {
				if(!(m.find(s)<=p))cnt++;
				next_permutation(m.begin(),m.end());
		}			
	}
	cout<<cnt<<endl;
	
	return 0;
}
