import java.io.ByteArrayInputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.PrintWriter;
import java.util.Arrays;
import java.util.InputMismatchException;

public class TEI {
	InputStream is;
	PrintWriter out;
	String INPUT = "";
	
	long sum(int b, int d)
	{
		long all = (-sumGPP(d+1, b, mod) * d + (long)d * b % mod * sumGP(d+1, b, mod)) % mod;
		if(all < 0)all += mod;
		return all;
	}
	
	void solve()
	{
		int n = ni(), b = ni(), d = ni();
		
		long[] lens = new long[40];
		long[] sums = new long[40];
		lens[1] = d;
		sums[1] = sum(1, d);
		for(int i = 2;i < 40;i++){
			lens[i] = lens[i-1] * (d+1) + d;
			sums[i] = sum(i, d);
		}
		long sum = 0;
		for(int i = 1;i < 40;i++){
			if(lens[i] > n){
				for(int j = i-1;j >= 0;j--){
					long k = n / (lens[j]+1);
					sum += k*(sums[j]+(j+1));
					sum %= mod;
					n -= k*(lens[j]+1);
					if(n == lens[j]){
						sum += sums[j];
						n = 0;
					}
					sum %= mod;
				}
				break;
			}
		}
		sum = sum(b, d) - sum;
		if(sum < 0)sum += mod;
		out.println(sum);
	}
	
	public static long sumGP(long a, long n, long mod)
	{
		long smul = 1; // % mod
		long mul = a % mod;
		long ret = 0;
		for(;n > 0;n >>>= 1){
			if((n&1)==1){
				ret = (ret * mul + smul) % mod;
			}
			smul = smul * (mul + 1) % mod;
			mul = mul * mul % mod;
		}
		return ret;
	}

	
	public long sumGPP(long a, long n, long mod)
	{
		long ssmul = 0; // % mod
		long smul = 1; // % mod
		long mul = a % mod;
		long gret = 0;
		long ret = 0;
		long mnum = 1; // % mod
		for(;n > 0;n >>>= 1){
			if((n&1)==1){
				gret = (gret * mul + ret * mul % mod * mnum + ssmul) % mod;
				ret = (ret * mul + smul) % mod;
			}
			ssmul = (ssmul * (mul+1) + smul * mul % mod * mnum) % mod;
			smul = smul * (mul + 1) % mod;
			mul = mul * mul % mod;
			mnum = 2 * mnum; if(mnum >= mod)mnum -= mod;
		}
		return gret;
	}

	
	public static final int mod = 1000000007;
	public static final long m2 = (long)mod*mod;
	public static final long BIG = 8L*m2;
	
	// A^e*v
	public static int[] pow(int[][] A, int[] v, long e)
	{
		for(int i = 0;i < v.length;i++){
			if(v[i] >= mod)v[i] %= mod;
		}
		int[][] MUL = A;
		for(;e > 0;e>>>=1) {
			if((e&1)==1)v = mul(MUL, v);
			MUL = p2(MUL);
		}
		return v;
	}
	
	// int matrix*int vector
	public static int[] mul(int[][] A, int[] v)
	{
		int m = A.length;
		int n = v.length;
		int[] w = new int[m];
		for(int i = 0;i < m;i++){
			long sum = 0;
			for(int k = 0;k < n;k++){
				sum += (long)A[i][k] * v[k];
				if(sum >= BIG)sum -= BIG;
			}
			w[i] = (int)(sum % mod);
		}
		return w;
	}
	
	// int matrix^2 (be careful about negative value)
	public static int[][] p2(int[][] A)
	{
		int n = A.length;
		int[][] C = new int[n][n];
		for(int i = 0;i < n;i++){
			long[] sum = new long[n];
			for(int k = 0;k < n;k++){
				for(int j = 0;j < n;j++){
					sum[j] += (long)A[i][k] * A[k][j];
					if(sum[j] >= BIG)sum[j] -= BIG;
				}
			}
			for(int j = 0;j < n;j++){
				C[i][j] = (int)(sum[j] % mod);
			}
		}
		return C;
	}

	
	void run() throws Exception
	{
		is = INPUT.isEmpty() ? System.in : new ByteArrayInputStream(INPUT.getBytes());
		out = new PrintWriter(System.out);
		
		long s = System.currentTimeMillis();
		solve();
		out.flush();
		if(!INPUT.isEmpty())tr(System.currentTimeMillis()-s+"ms");
//		Thread t = new Thread(null, null, "~", Runtime.getRuntime().maxMemory()){
//			@Override
//			public void run() {
//				long s = System.currentTimeMillis();
//				solve();
//				out.flush();
//				if(!INPUT.isEmpty())tr(System.currentTimeMillis()-s+"ms");
//			}
//		};
//		t.start();
//		t.join();
	}
	
	public static void main(String[] args) throws Exception { new TEI().run(); }
	
	private byte[] inbuf = new byte[1024];
	public int lenbuf = 0, ptrbuf = 0;
	
	private int readByte()
	{
		if(lenbuf == -1)throw new InputMismatchException();
		if(ptrbuf >= lenbuf){
			ptrbuf = 0;
			try { lenbuf = is.read(inbuf); } catch (IOException e) { throw new InputMismatchException(); }
			if(lenbuf <= 0)return -1;
		}
		return inbuf[ptrbuf++];
	}
	
	private boolean isSpaceChar(int c) { return !(c >= 33 && c <= 126); }
	private int skip() { int b; while((b = readByte()) != -1 && isSpaceChar(b)); return b; }
	
	private double nd() { return Double.parseDouble(ns()); }
	private char nc() { return (char)skip(); }
	
	private String ns()
	{
		int b = skip();
		StringBuilder sb = new StringBuilder();
		while(!(isSpaceChar(b))){ // when nextLine, (isSpaceChar(b) && b != ' ')
			sb.appendCodePoint(b);
			b = readByte();
		}
		return sb.toString();
	}
	
	private char[] ns(int n)
	{
		char[] buf = new char[n];
		int b = skip(), p = 0;
		while(p < n && !(isSpaceChar(b))){
			buf[p++] = (char)b;
			b = readByte();
		}
		return n == p ? buf : Arrays.copyOf(buf, p);
	}
	
	private int[] na(int n)
	{
		int[] a = new int[n];
		for(int i = 0;i < n;i++)a[i] = ni();
		return a;
	}
	
	private long[] nal(int n)
	{
		long[] a = new long[n];
		for(int i = 0;i < n;i++)a[i] = nl();
		return a;
	}
	
	private char[][] nm(int n, int m) {
		char[][] map = new char[n][];
		for(int i = 0;i < n;i++)map[i] = ns(m);
		return map;
	}
	
	private int[][] nmi(int n, int m) {
		int[][] map = new int[n][];
		for(int i = 0;i < n;i++)map[i] = na(m);
		return map;
	}
	
	private int ni() { return (int)nl(); }
	
	private long nl()
	{
		long num = 0;
		int b;
		boolean minus = false;
		while((b = readByte()) != -1 && !((b >= '0' && b <= '9') || b == '-'));
		if(b == '-'){
			minus = true;
			b = readByte();
		}
		
		while(true){
			if(b >= '0' && b <= '9'){
				num = num * 10 + (b - '0');
			}else{
				return minus ? -num : num;
			}
			b = readByte();
		}
	}
	
	private static void tr(Object... o) { System.out.println(Arrays.deepToString(o)); }
}