1
 2
 3
 4
 5
 6
 7
 8
 9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
#include <iostream>
using namespace std;

long long dp[1005][1005];
long long dp2[1005][1005];
int n, m, p;
long long calc(int l, int i)
{
    long long ans = 0;
    for (int s = 1; s <=m; s++)
    {
        ans += dp[s][min(i + l - 1, m - s + 1)] - dp[s][max (1, i - s + 1) - 1];
        if (ans < 0) ans += p;
        if (ans >= p) ans -= p;
        /*for (int k = max (1, i - s + 1); k <= i + l - 1; k++)
        {
            ans += dp[s][k];
            if (ans >= p) ans -= p;
        }*/
    }
    return ans;
}

int main()
{
    ios_base::sync_with_stdio(false);
    cin.tie(0);
    cout.tie(0);

    cin >> n >> m >> p;
    for (int l = 1; l <= m; l++)
    {
        for (int i = 1; i + l - 1 <= m; i++)
        {
            dp[l][i] = dp[l][i - 1] + 1;
            dp2[l][i] = 1;
        }
    }
    //cout << dp[1][1] << dp[1][2] << dp[2][1] << dp[2][2] << "\n";
    for (int j = 1; j < n; j++)
    {
        for (int l = 1; l <= m; l++)
        {
            for (int i = 1; i + l - 1 <= m; i++)
            dp2[l][i] = calc(l, i);
        }
        //cout << dp2[1][1] << dp2[1][2] << dp2[2][1] << dp2[2][2] << "\n";
        for (int l = 1; l <= m; l++)
        {
            for (int i = 1; i + l - 1 <= m; i++)
            {
                dp[l][i] = dp[l][i -1] + dp2[l][i];
            }
        }
        //cout << dp[1][1] << dp[1][2] << dp[2][1] << dp[2][2] << "\n";
    }
    long long odp = 0;
    for (int l = 1; l <= m; l++)
    {
        for (int i = 1; i <= m; i++)
        {
            odp += dp2[l][i];
            if (odp >= p) odp -= p;
        }
    }
    cout << odp;
}