下面程序的输出为（ ）。
1 #include <iostream>
2 using namespace std;
3
4 int a[10][10];
5 int main() {
6 int m = 5, n = 4;
7 for (int x = 0; x <= m; x++)
8 a[x][0] = 1;
9 for (int y = 1; y <= n; y++)
10 a[0][y] = 1;
11 for (int x = 1; x <= m; x++)
12 for (int y = 1; y <= n; y++)
13 a[x][y] = a[x - 1][y] + a[x][y - 1];
14 cout << a[m][n] << endl;
15 return 0;
16 }
4
5
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