#pragma GCC optimize ("O3")
// #pragma GCC target ("avx")
#include<stdio.h>
#include<iostream>
#include<vector>
#include<algorithm>
#include<string>
#include<string.h>

#ifdef LOCAL
#define eprintf(...) fprintf(stderr, __VA_ARGS__)
#else
#define NDEBUG
#define eprintf(...) do {} while (0)
#endif
#include<cassert>

using namespace std;

typedef long long LL;
typedef vector<int> VI;

#define REP(i,n) for(int i=0, i##_len=(n); i<i##_len; ++i)
#define EACH(i,c) for(__typeof((c).begin()) i=(c).begin(),i##_end=(c).end();i!=i##_end;++i)

template<class T> inline void amin(T &x, const T &y) { if (y<x) x=y; }
template<class T> inline void amax(T &x, const T &y) { if (x<y) x=y; }
template<class Iter> void rprintf(const char *fmt, Iter begin, Iter end) {
    for (bool sp=0; begin!=end; ++begin) { if (sp) putchar(' '); else sp = true; printf(fmt, *begin); }
    putchar('\n');
}

template<unsigned MOD_> struct ModInt {
    static constexpr unsigned MOD = MOD_;
    unsigned x;
    void undef() { x = (unsigned)-1; }
    bool isnan() const { return x == (unsigned)-1; }
    inline int geti() const { return (int)x; }
    ModInt() { x = 0; }
    ModInt(const ModInt &y) { x = y.x; }
    ModInt(int y) { if (y<0 || (int)MOD<=y) y %= (int)MOD; if (y<0) y += MOD; x=y; }
    ModInt(unsigned y) { if (MOD<=y) x = y % MOD; else x = y; }
    ModInt(long long y) { if (y<0 || MOD<=y) y %= MOD; if (y<0) y += MOD; x=y; }
    ModInt(unsigned long long y) { if (MOD<=y) x = y % MOD; else x = y; }
    ModInt &operator+=(const ModInt y) { if ((x += y.x) >= MOD) x -= MOD; return *this; }
    ModInt &operator-=(const ModInt y) { if ((x -= y.x) & (1u<<31)) x += MOD; return *this; }
    ModInt &operator*=(const ModInt y) { x = (unsigned long long)x * y.x % MOD; return *this; }
    ModInt &operator/=(const ModInt y) { x = (unsigned long long)x * y.inv().x % MOD; return *this; }
    ModInt operator-() const { return (x ? MOD-x: 0); }

    ModInt inv() const { return pow(MOD-2); }
    ModInt pow(long long y) const {
	ModInt b = *this, r = 1;
	if (y < 0) { b = b.inv(); y = -y; }
	for (; y; y>>=1) {
	    if (y&1) r *= b;
	    b *= b;
	}
	return r;
    }

    friend ModInt operator+(ModInt x, const ModInt y) { return x += y; }
    friend ModInt operator-(ModInt x, const ModInt y) { return x -= y; }
    friend ModInt operator*(ModInt x, const ModInt y) { return x *= y; }
    friend ModInt operator/(ModInt x, const ModInt y) { return x *= y.inv(); }
    friend bool operator<(const ModInt x, const ModInt y) { return x.x < y.x; }
    friend bool operator==(const ModInt x, const ModInt y) { return x.x == y.x; }
    friend bool operator!=(const ModInt x, const ModInt y) { return x.x != y.x; }
};

constexpr LL MOD = 1000000007;
using Mint = ModInt<MOD>;

int N;
int A, B;

Mint aFa[10011];
Mint aFb[10011];
Mint bFb[10011];

Mint dp0[10011];
Mint dp1[10011];
Mint dp2[10011];
Mint dp3[10011];
Mint dp4[10011];


void MAIN() {
    scanf("%d%d%d", &N, &A, &B);
    if (A > B) swap(A, B);
    aFa[A] = 1;
    for (int i=A; i<N; i++) {
	// b;
	aFa[i+1] += aFa[i];
	// baaaaa;
	for (int a=A; a+i<=N; a++) aFa[i+a+1] += aFa[i];
    }

    for (int a=A; a<N; a++) aFb[a+1] = 1;
    for (int i=A+1; i<N; i++) {
	// b;
	aFb[i+1] += aFb[i];
	// aaaaab;
	for (int a=A; a+i<=N; a++) aFb[i+a+1] += aFb[i];
    }

    bFb[1] = 1;
    for (int i=1; i<N; i++) {
	// b;
	bFb[i+1] += bFb[i];
	// aaaaab;
	for (int a=A; a+i<=N; a++) bFb[i+a+1] += bFb[i];
    }


    Mint ans = 0;

    for (int a=1; a<A; a++) {
	dp0[a] += 1;
    }
    for (int b=1; b<B; b++) {
	dp1[b] += bFb[b];
	dp1[b] += aFb[b];
    }
    for (int b=B; b<N; b++) {
	dp2[b] += bFb[b];
	dp2[b] += aFb[b];
    }

    ans += aFa[N];
    ans += aFb[N] * 2;
    ans += bFb[N];

    //eprintf("%d\n", aFa[N].geti());
    //eprintf("%d\n", aFb[N].geti());
    //eprintf("%d\n", bFb[N].geti());
    //eprintf("%d\n", ans.geti());

    for (int i=1; i<N; i++) {
	for (int a=1; a<A; a++) {
	    dp0[i+a] += dp1[i];
	}

	for (int b=1; b<B; b++) {
	    dp1[i+b] += dp0[i] * bFb[b];
	}

	for (int b=B; b+i<N; b++) {
	    dp2[i+b] += dp0[i] * bFb[b];
	}

	if (N-i >= B) {
	    ans += dp0[i] * bFb[N-i];
	    ans += dp0[i] * aFb[N-i]; // bFa;
	}

	for (int a=1; a<A; a++) {
	    dp3[i+a] += dp2[i];
	}

	// b;
	dp4[i+1] += dp3[i];
	// a or b;
	dp4[i+1] += dp4[i] * 2;
    }

    ans += dp3[N] + dp4[N];

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

int main() {
    int TC = 1;
//    scanf("%d", &TC);
    REP (tc, TC) MAIN();
    return 0;
}



Measured memory_bytes: 4144