求调

#include <iostream>
using namespace std;
long long a, b, c, f[25][25][25]; 
long long w(int a, int b, int c)
{
	if (a <= 0 or b <= 0 or c <= 0)
	{
	    return 1;
	}
	else if (a > 20 or b > 20 or c > 20)
	{
	    return w(20 , 20 , 20);
	}
	else if (f[a][b][c])
	{
	    return f[a][b][c];
	}
	else if (a < b and b < c)
	{
	    f[a][b][c] = w(a , b , c - 1) + w(a , b - 1 , c - 1) - w(a , b - 1 , c);
	    return f[a][b][c];
	}
	else
	{
	    f[a][b][c] = w(a - 1 , b , c) + w(a - 1 , b - 1 , c) + w(a - 1 , b , c - 1) - w(a - 1 , b - 1 , c - 1);
	    return f[a][b][c];
	}
} 
int main()
{
	while (true)
	{
		cin >> a >> b >> c;
		if (a == -1 and b == -1 and c == -1)
		{
		    break;
		}
		cout << "w(" << a << ", " << b << ", " << c << ") = " << w(a , b , c) << endl;
	}
    return 0;
}