#include <bits/stdc++.h>   using namespace std;   template <class T>   T abs(T x) {     return x > 0 ? x : (-x);   }   template <class T>   T sqr(T x) {     return x * x;   }   const int maxn = 1000 * 1000 * 2;   const int BUBEN = 40;   long long fib[BUBEN];   int a[maxn];   int n;   long long X, Y;   long long P;   struct M {     long long a[2][2];     M() { memset(a, 0, sizeof(a)); }     long long* operator[](int x) { return a[x]; }     M operator*(M m) {       M res;       for (int i = 0; i < 2; ++i)         for (int j = 0; j < 2; ++j)           for (int k = 0; k < 2; ++k)             res[i][j] = (res[i][j] + a[i][k] * m[k][j]) % P;       return res;     }   };   M pw(M x, long long y) {     M res;     res[0][0] = res[1][1] = 1;     while (y) {       if (y % 2LL == 1LL)         res = res * x, --y;       else         x = x * x, y /= 2LL;     }     return res;   }   const double alpha = (1. + sqrt(5.)) * 0.5;   bool cmp(pair<long long, long long> p, pair<long long, long long> q) {     if (X >= BUBEN - 2)       return p.first * alpha + p.second > q.first * alpha + q.second;     return p.first * fib[X + 1] + p.second * fib[X] >            q.first * fib[X + 1] + q.second * fib[X];   }   int main() {     fib[0] = 0;     fib[1] = 1;     for (int i = 2; i < BUBEN; ++i) fib[i] = fib[i - 1] + fib[i - 2];     cin >> n >> X >> Y >> P;     long long sum = 0;     for (int i = 0; i < n; ++i) {       scanf( %d , &a[i]);       sum += a[i];       sum %= P;     }     sort(a, a + n);     if (0) {       vector<int> v;       for (int i = 0; i < n; ++i) v.push_back(a[i]);       for (int i = 0; i < X; ++i) {         vector<int> w;         w.push_back(v[0]);         for (int j = 1; j < ((int)(v).size()); ++j)           w.push_back(v[j - 1] + v[j]), w.push_back(v[j]);         v = w;       }       sort((v).begin(), (v).end());       for (int i = 0; i < Y; ++i) {         vector<int> w;         w.push_back(v[0]);         for (int j = 1; j < ((int)(v).size()); ++j)           w.push_back(v[j - 1] + v[j]), w.push_back(v[j]);         v = w;       }       long long res = 0;       for (int i = 0; i < ((int)(v).size()); ++i) res += v[i];       res %= P;       cerr << res <<   n ;     }     if (n == 1) {       cout << (a[0] % P) <<   n ;       return 0;     }     long long l1 = a[0], r1 = a[n - 1];     long long l2 = a[0];     pair<long long, long long> _r2(-1, -1);     for (int i = 0; i < n - 1; ++i) {       long long x = a[i], y = a[i + 1];       if (x < y) swap(x, y);       pair<long long, long long> cur(x, y);       if (cmp(cur, _r2)) _r2 = cur;     }     M mf;     mf[0][0] = mf[0][1] = mf[1][0] = 1;     M F = pw(mf, X);     long long r2 = F[0][0] * (_r2.first % P) + F[0][1] * (_r2.second % P);     r2 %= P;     M m1;     m1[0][0] = 3;     m1[0][1] = (P - 1) % P;     m1[1][1] = 1;     M m2 = pw(m1, X);     long long T1 = l1 + r1;     long long T2 = l2 + r2;     T1 %= P;     T2 %= P;     long long s0 = m2[0][0] * sum + m2[0][1] * (T1);     s0 %= P;     M m3 = pw(m1, Y);     long long res = m3[0][0] * s0 + m3[0][1] * (T2);     res %= P;     res += P;     res %= P;     cout << res <<   n ;     return 0;   }   