#include <iostream>
#include <sstream>
#include <fstream>
#include <iomanip>
#include <cstdio>
#include <cstdlib>
#include <algorithm>
#include <queue>
#include <stack>
#include <set>
#include <map>
#include <list>
#include <vector>
#include <string>
#include <cstring>
#include <cmath>
#include <ctime>
#include <cassert>
#include <bitset>

using namespace std;

#define forn(i, n) for(int i = 0; i < (int)(n); i++)
#define forn1(i, n) for(int i = 1; i <= (int)(n); i++)
#define forr(i, l, r) for(int i = int(l); i <= int(r); i++)
#define all(a) (a).begin(), (a).end()
#define sz(a) (int)((a).size())
#define mp make_pair
#define pb push_back
#define x first
#define y second
#define y1 __y1
#define sqr(x) ((x) * (x))

typedef long long li;
typedef long double ld;
typedef pair<int, int> pt;

const int INF = (int)(1e9);
const li INF64 = (li)(INF) * (li)(INF);
const ld eps = 1e-9;
const ld pi = ld(3.1415926535897932384626433832795);

inline bool in(int i, int j, int n, int m)
{
    return i >= 1 && i <= n && j >= 1 && j <= m;
}

inline int myrand()
{
    return (rand() ^ (rand() << 15));
}

const int dx[] = {-1, 0, 1, 0};
const int dy[] = {0, 1, 0, -1};

const int N = 111;

char a[N], b[N];
int n, m, L;

inline void gen()
{
    return;
}

inline bool read()
{
    string s1, s2;
    assert(cin >> s1 >> s2);
    n = sz(s1);
    forn(i, n) a[i + 1] = s1[i];
    m = sz(s2);
    forn(i, m) b[i + 1] = s2[i];
    assert(cin >> L);
    return true;
}

const int MOD = INF + 7;

inline void add(int &a, const int &b)
{
    a += b;
    if(a >= MOD) a -= MOD;
    return;
}

int dp[N][N][N];
int leftMostA[N][256], leftMostB[N][256];
int lf[256];

inline void solve()
{
    forn(i, 256) lf[i] = INF;
    for(int i = n; i >= 0; i--)
    {
        for(char c = 'a'; c <= 'z'; c++)
        {
            leftMostA[i][c] = lf[c];
        }

        lf[a[i]] = i;
    }

    forn(i, 256) lf[i] = INF;
    for(int i = m; i >= 0; i--)
    {
        for(char c = 'a'; c <= 'z'; c++)
        {
            leftMostB[i][c] = lf[c];
        }

        lf[b[i]] = i;
    }

    forn(i, N) forn(j, N) forn(k, N) assert(dp[i][j][k] == 0);
    dp[0][0][0] = 1;
    for(int i = 0; i < n; i++)
    {
        for(int j = 0; j < m; j++)
        {
            for(int len = 0; len < n; len++)
            {
                int cur = dp[i][j][len];
                if(cur == 0) continue;
                for(char c = 'a'; c <= 'z'; c++)
                {
                    int ni = leftMostA[i][c];
                    int nj = leftMostB[j][c];
                    if(ni <= n && nj <= m)
                    {
                        assert(a[ni] == b[nj]);
                        assert(a[ni] == c);
                        add(dp[ni][nj][len + 1], cur);
                    }
                }
            }
        }
    }

    int ans = 0;
    forn(i, N) forn(j, N) add(ans, dp[i][j][L]);
    cout << ans << endl;
    return;
}

int main()
{
#ifdef _DEBUG
    assert(freopen("input.txt", "rt", stdin));
    assert(freopen("output.txt", "wt", stdout));
#endif

    cout << setprecision(10) << fixed;
    cerr << setprecision(10) << fixed;

    srand(int(time(NULL)));

    int T = 1;
    //assert(scanf("%d", &T) == 1);

    forn(i, T)
    {
        assert(read());
        solve();
    }

#ifdef _DEBUG
    cerr << "TIME == " << clock() << " ms" << endl;
#endif
    return 0;
}