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| #include <cstdio>
using namespace std;
template <class Type>
void read(Type &x)
{
char c;
bool flag = false;
while ((c = getchar()) < '0' || c > '9')
c == '-' && (flag = true);
x = c - '0';
while ((c = getchar()) >= '0' && c <= '9')
x = (x << 3) + (x << 1) + c - '0';
if (flag) x = ~x + 1;
}
template <class Type, class ...rest>
void read(Type &x, rest &...y) { read(x), read(y...); }
template <class Type>
void write(Type x)
{
if (x < 0) putchar('-'), x = ~x + 1;
if (x > 9) write(x / 10);
putchar(x % 10 + '0');
}
typedef long long LL;
const int N = 3e3 + 10, mod = 1e9 + 7;
void adj (int &x) { x += x >> 31 & mod; }
int n, m, f[N][N];
bool mp[N][N];
int calc (int sx, int sy, int ex, int ey)
{
for (int i = 1; i <= n; ++i)
for (int j = 1; j <= m; ++j)
f[i][j] = 0;
f[sx][sy] = mp[sx][sy];
for (int i = 1; i <= n; ++i)
for (int j = 1; j <= m; ++j) if (mp[i][j])
adj(f[i][j] += f[i - 1][j] - mod), adj(f[i][j] += f[i][j - 1] - mod);
return f[ex][ey];
}
int main ()
{
read(n, m);
for (int i = 1; i <= n; ++i)
for (int j = 1; j <= m; ++j)
{
char c = getchar();
while (c != '.' && c != '#') c = getchar();
mp[i][j] = c == '.';
}
write(((LL)calc(1, 2, n - 1, m) * calc(2, 1, n, m - 1) % mod - (LL)calc(1, 2, n, m - 1) * calc(2, 1, n - 1, m) % mod + mod) % mod);
return 0;
}
|