Problem:
Score : 100 points

Problem Statement

There is a grid with H horizontal rows and W vertical columns.
Let (i, j) denote the square at the i-th row from the top and the j-th column from the left.

For each i and j (1 \leq i \leq H, 1 \leq j \leq W), Square (i, j) is described by a character a_{i, j}.
If a_{i, j} is ., Square (i, j) is an empty square; if a_{i, j} is #, Square (i, j) is a wall square.
It is guaranteed that Squares (1, 1) and (H, W) are empty squares.

Taro will start from Square (1, 1) and reach (H, W) by repeatedly moving right or down to an adjacent empty square.

Find the number of Taro's paths from Square (1, 1) to (H, W).
As the answer can be extremely large, find the count modulo 10^9 + 7.

Constraints

H and W are integers.

2 \leq H, W \leq 1000

a_{i, j} is . or #.

Squares (1, 1) and (H, W) are empty squares.

Input

Input is given from Standard Input in the following format:

H W
a_{1, 1}\ldotsa_{1, W}
:
a_{H, 1}\ldotsa_{H, W}

Output

Print the number of Taro's paths from Square (1, 1) to (H, W), modulo 10^9 + 7.

Sample Input 1

3 4
...#
.#..
....

Sample Output 1

3

There are three paths as follows:

Sample Input 2

5 2
..
#.
..
.#
..

Sample Output 2

0

There may be no paths.

Sample Input 3

5 5
..#..
.....
#...#
.....
..#..

Sample Output 3

24

Sample Input 4

20 20
....................
....................
....................
....................
....................
....................
....................
....................
....................
....................
....................
....................
....................
....................
....................
....................
....................
....................
....................
....................

Sample Output 4

345263555

Be sure to print the count modulo 10^9 + 7.

Solution in C++ (GCC 9.2.1) (judge verdict: Runtime Error)

                                  //ABHISHEK AGRAWAL//                    
                      //Newbie......You have to be odd to be no. ONE :)//
#include<bits/stdc++.h>
using namespace std;
#define ll long long int
#define ld long double
#define fl float
#define lcm(a,b) (a*(b/__gcd(a,b)))
#define vs vector <string>
#define vc vector <char>
#define vll vector<ll>
#define sll set<ll>
#define pll pair<ll,ll>
#define plc pair<ll,char>
#define tlll tuple<ll,ll,ll>
#define mt make_tuple
#define vpll vector<pair<ll,ll>>
#define vtll vector<tuple<ll,ll,ll>>
#define vvll vector<vector<ll>>
#define lb lower_bound
#define pb push_back
#define pob pop_back
#define f first
#define s second
#define mll map<ll,ll>
#define mp make_pair
#define sp(n) fixed<<setprecision(n)
#define mcl map<char,ll>
#define mcc map<char,char>
#define msl map<string,ll>
#define mss map<string,string>  
#define mod (ll)1000000007
#define flash ios_base::sync_with_stdio(false);cin.tie(NULL);cout.tie(NULL); 
#define test ll t;read(t);while(t--) 
#define sortv(v) sort(v.begin(),v.end())
#define INF (ll)(1e15)
#define loop(i,n) for(ll i=0;i<n;i++)
#define loop1(i,n) for(ll i=1;i<=n;i++)
#define rloop(n,i) for(ll i=n-1;i>=0;i--)
#define loopab(i,a,b,c) for(ll i=a;i<=b;i+=c)
#define max3(a,b,c) max(max(a,b),c)
#define min3(a,b,c) min(min(a,b),c)
#define reada(a,n) loop(i,n) cin>>a[i];
#define reada1(a,n) loop1(i,n) cin>>a[i];
#define sorta(a) sort(a,a+n,greater<ll>())
#define countone(n) __builtin_popcount(n)
#define numoftrailzero(n) __builtin_ctz(n)
#define maxpowoftwo(n) __builtin_clz(n)
#define leastindexwithone(n)  __builtin_ffs(n)
#define what_is(x) cerr << #x << " is " << x << endl;
#define pfv(v) cout<<v.size()<<"\n";loop(i,v.size()) cout<<v[i]<<" ";
#define pv(v) loop(i,v.size()) cout<<v[i]<<" ";
//if we need to devide any given number in powers of term the power of max term
#define answer(n) ceil(log2(n+1))
ll n,q;
ll gcd(ll a, ll b){if (b==0){return a;} return gcd(b,a%b);}
ll powe(ll a,ll b){ll res=1;while(b>0){if(b%2 ==1){res=(res*a);}a=(a*a);b/=2;} return res;}
ll power(ll a,ll b,ll M){a%=M;ll res=1;while(b>0){if(b%2 ==1){res=(res*a)%M;}a=(a*a)%M;b/=2;} return res;}
ll extendedEuclid(ll A,ll B,ll &x,ll &y){
    if(B == 0) {
        x = 1;
        y = 0;
        return A;
    }
    else {
        ll x1 , y1;
        ll gcd = extendedEuclid(B,A%B,x1,y1);
        y = x1-(A/B)*y1; 
        x = y1;
        return gcd;
    }
}
ll mi(ll A, ll M){ll x,y;extendedEuclid(A,M,x,y);if(x<0){x+=mod;} return x;}
 
 
template <typename T>
void read(T &x) {
    cin >> x;
}
template <typename T , typename T0>
void read(T &x, T0 &y) {
    cin >> x >> y;
}
template <typename T , typename T0 , typename T1>
void read(T &x, T0 &y, T1 &z) {
    cin >> x >> y >> z;
}
template <typename T , typename T0 , typename T1 , typename T2>
void read(T &x, T0 &y, T1 &z, T2 &w) {
    cin >> x >> y >> z >> w;
}
 
//pair//
//read pair//
template <typename T , typename T0>
void read(pair< T , T0 > &p) {
    cin >> p.f >> p.s;
}
//write pair//
template <typename T , typename T0>
void write(pair< T , T0 > &p){
    write(p.f);
    write(p.s);
}
 
//vector//
//read vector//
template <typename T>
void read(vector< T > &oneD, ll n) {
    loop(i,n)
    {
        ll x;
        read(x);
        oneD.pb(x);
    }
}
//array//
//read array//
template <typename T>
void read(T oneD[] , ll n) {
    loop(i,n){
        read(oneD[i]);
    }
}
//write array//
template <typename T>
void write(T oneD[] ,int n){
    loop(i,n){
        write(oneD[i]);
    }
    cout << endl;
}

vector<bool>sieve(1000000,true);
void Sieve(){
 sieve[0]=false;
 sieve[1]=false;
 for(ll i=2;i*i<=1000000;i++){
  if(sieve[i]==true){
   for(ll j=i*i;j<1000000;j+=i)
    sieve[j]=false;
  }
 }
}
 vll sieve_spf;
void Sieve_spf(){
 const ll n = 1e6 + 5;
 sieve_spf.resize(n);
 
 loop(i,n)
  sieve_spf[i]=i;
 
 sieve_spf[0]=-1;
 sieve_spf[1]=1;
 
 loopab(i,2,n,2)
  sieve_spf[i]=2;
 
 loopab(i,3,n,2)
  if(sieve_spf[i]==i)
   loopab(j,i*i,n,i)
    if(sieve_spf[j]==j)
     sieve_spf[j]=i;
}
bool oppositeSigns(ll x,ll y) 
{ 
    return ((x^y)<0); 
} 
int mpt(ll n){
    ll c=0;
     ll n1=pow(2,c);
     while(n1<n){
         c++;
         n1=pow(2,c);
     }
     return c;
}
void the_happiest_place_on_earth()
{
    flash;
  #ifdef ENABLE_FILE_IO
    freopen("in", "r", stdin);
    freopen("out", "w", stdout);
  #endif      
}
const int N=1001,M=1001;ll a[N][M],dp[N][M];
void solve(){
    ll m;read(n,m);ll n1=0,m1=0;
    loop(i,n) loop(j,m) {char c;read(c);if(c=='#') a[i][j]=1;else a[i][j]=0;dp[i][j]=0;}
    ll i=0,j=0;
    while(a[i][j]==0) dp[i][j]=1,j++;
    i=0,j=0;
    while(a[i][j]==0) dp[i][j]=1,i++;
    loop1(i,n-1){
        loop1(j,m-1){
            if(a[i][j-1]==0) dp[i][j]+=dp[i][j-1]%mod;
            if(a[i-1][j]==0) dp[i][j]+=dp[i-1][j]%mod;
            dp[i][j]%=mod;
        }
    }
    cout<<dp[n-1][m-1];
    return;
}
int main(){
    the_happiest_place_on_earth();
    //Today's thought: Push yourself, because no one else is going to do it for you.
    //Things aren’t always #000000 and #FFFFFF
    //START OF PROGRAM LOGIC
    solve();
    cerr << "Time : " << 1000 * ((double)clock()) / (double)CLOCKS_PER_SEC << "ms\n";
    //END OF PROGRAM LOGIC
	return 0;
}