#include<bits/stdc++.h>
using namespace std;

using ll = long long;

const int MAXN = 8005;
const int Mod = 998244353;

int S[MAXN][MAXN], iFac[MAXN], inv[MAXN], Fac[MAXN];

int Fpow(int x, int k) {
    int ans = 1;
    for (x %= Mod; k; k >>= 1, x = 1ll * x * x % Mod) {
        if (k & 1) ans = 1ll * ans * x % Mod;
    }
    return ans;
}

void solve() {
    int maxN = 8001; 
    S[0][0] = 1;
    for (int i = 1; i <= maxN; i++) {
        S[i][0] = 0;
        for (int j = 1; j <= i; j++) {
            S[i][j] = (1ll * S[i - 1][j] * j + S[i - 1][j - 1]) % Mod;
        }
    } 
    inv[0] = 1;
    for (int i = 1; i <= maxN; i++) {
        inv[i] = Fpow(i, Mod - 2);
    }
    iFac[0] = 1;
    for (int i = 1; i <= maxN; i++) {
        iFac[i] = 1ll * iFac[i - 1] * inv[i] % Mod;
    }
    Fac[0] = 1;
    for (int i = 1; i <= maxN; i++) {
        Fac[i] = 1ll * Fac[i - 1] * i % Mod;
    }
    int t;
    cin >> t;
    while(t--){
        int n, m;
        cin >> n >> m;
        int ans = ((Fpow((1 + inv[m]), n) % Mod
                    - 1 
                    - 1ll * Fpow(inv[m], n) % Mod * S[n][m + 1] % Mod * Fac[n] % Mod) % Mod + Mod) % Mod;
        cout << ans << '\n';
    }
}

signed main() {
    ios::sync_with_stdio(false);
    cin.tie(0), cout.tie(0);
    int t = 1;
    // cin >> t;
    while(t--) solve();
    return 0;
}