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
#include <bits/stdc++.h>


using namespace std;


int solve(int n, int m, int p) {
    vector <int> dp(m + 1, 0);
    dp[m] = 1;

    while (n--) {
        vector <int> dpNew(m + 1, 0);

        int sumPref = 0;

        for (int i = 1; i <= m; i++) {
            int diff = dp[m] - dp[m - i];
            if (diff < 0) {
                diff += p;
            }

            sumPref -= dp[i - 1];
            if (sumPref < 0) {
                sumPref += p;
            }

            dpNew[i] = (dpNew[i - 1] + (long long) diff * i + sumPref) % p;
        }

        dp = dpNew;
    }

    return dp.back();
}


int main() {
    ios_base::sync_with_stdio(false);

    int n, m, p;
    cin >> n >> m >> p;

    cout << solve(n, m, p) << '\n';

    return 0;
}