// Copyright (C) 2017 __debug.

// This program is free software; you can redistribute it and/or
// modify it under the terms of the GNU General Public License as
// published by the Free Software Foundation; version 3

// This program is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
// GNU General Public License for more details.

// You should have received a copy of the GNU General Public License
// along with this program; If not, see <http://www.gnu.org/licenses/>.


#include <bits/stdc++.h>
#include <ext/pb_ds/assoc_container.hpp>
#include <ext/pb_ds/priority_queue.hpp>

#define x first
#define y second
#define MP std::make_pair
#define SZ(x) ((int)(x).size())
#define ALL(x) (x).begin(), (x).end()
#define DEBUG(...) fprintf(stderr, __VA_ARGS__)
#ifdef __linux__
#define getchar getchar_unlocked
#define putchar putchar_unlocked
#endif

using std::pair;
using std::vector;
using std::string;

typedef long long LL;
typedef pair<int, int> Pii;

const int oo = 0x3f3f3f3f;

template<typename T> inline bool chkmax(T &a, T b) { return a < b ? a = b, true : false; }
template<typename T> inline bool chkmin(T &a, T b) { return b < a ? a = b, true : false; }
string procStatus()
{
    std::ifstream t("/proc/self/status");
    return string(std::istreambuf_iterator<char>(t), std::istreambuf_iterator<char>());
}
template<typename T> T read(T &x)
{
    int f = 1;
    char ch = getchar();
    for (; !isdigit(ch); ch = getchar())
        f = (ch == '-' ? -1 : 1);
    for (x = 0; isdigit(ch); ch = getchar())
        x = 10 * x + ch - '0';
    return x *= f;
}
template<typename T> void write(T x)
{
    if (x == 0) {
        putchar('0');
        return;
    }
    if (x < 0) {
        putchar('-');
        x = -x;
    }
    static char s[20];
    int top = 0;
    for (; x; x /= 10)
        s[++top] = x % 10 + '0';
    while (top)
        putchar(s[top--]);
}
// EOT

const int MAXN = 4e3 + 5;
const int MOD = 1e9 + 7;

int N, M, K;

void input()
{
    read(M); read(N); read(K);
}

void solve()
{
    static int dp[MAXN][MAXN][2];
    int t = (N + M - 1) / (K - 1);

    dp[0][0][0] = 1;
    for (int i = 0; i < t; ++i) {
        for (int x = 0; x <= N; ++x) {
            for (int j = 0; j <= 1; ++j) {
                if (!dp[i][x][j])
                    continue;
                int y = i * (K - 1) - x;
                // printf("%d %d %d %d: %d\n", i, x, y, j, dp[i][x][j]);
                for (int z = 0; z < K; ++z) {
                    int x0 = x + z, y0 = y + K - 1 - z;
                    if (x0 <= N && y0 <= M - 1)
                        (dp[i + 1][x0][!!z] += dp[i][x][j]) %= MOD;
                }
            }
        }
    }

    int ans = 0;
    for (int i = 0; i <= t; ++i) {
        for (int x = 0; x <= N && i * (K - 1) - x >= 0; ++x) {
            int y = i * (K - 1) - x;
            if (x % (K - 1) == N % (K - 1) && y % (K - 1) == (M - 1) % (K - 1)) {
                // printf("%d %d %d\n", x, y, dp[i][x][1]);
                (ans += dp[i][x][1]) %= MOD;
            }
        }
    }

    printf("%d\n", ans);
}

int main()
{
#ifdef __DEBUG
    freopen("E.in", "r", stdin);
    freopen("E.out", "w", stdout);
#endif

    input();
    solve();

    return 0;
}

// 人生如寄，何事辛苦怨斜晖。
//     -- 朱熹《水调歌头·隐括杜牧之齐山诗》


Measured memory_bytes: 113280