P5431TLE,30分，请问还能咋优化？？

#include<bits/stdc++.h>
#define ll long long
using namespace std;
ll p,a[5000010];
inline ll ksm(ll a,ll b) {
    ll ans = 1;
    while (b) {
        if (b & 1) ans = ans * a % p;
        a = a * a % p;
        b >>= 1;
    }
    return ans;
}
int main(){
    int n,k;
    scanf("%d %lld %d",&n,&p,&k);
    for (int i = 1;i <= n;i ++) {
        scanf("%lld",&a[i]);
    }
    ll ans = 0;
    for (int i = 1;i <= n;i ++) {
        ans += ksm(k,i) * ksm(a[i],p - 2) % p;
        ans %= p;
    }
    cout << ans % p << endl;
    return 0;
}