import std.conv, std.functional, std.range, std.stdio, std.string;
import std.algorithm, std.array, std.bigint, std.bitmanip, std.complex, std.container, std.math, std.mathspecial, std.numeric, std.regex, std.typecons;
import core.bitop;

class EOFException : Throwable { this() { super("EOF"); } }
string[] tokens;
string readToken() { for (; tokens.empty; ) { if (stdin.eof) { throw new EOFException; } tokens = readln.split; } auto token = tokens.front; tokens.popFront; return token; }
int readInt() { return readToken.to!int; }
long readLong() { return readToken.to!long; }
real readReal() { return readToken.to!real; }

bool chmin(T)(ref T t, in T f) { if (t > f) { t = f; return true; } else { return false; } }
bool chmax(T)(ref T t, in T f) { if (t < f) { t = f; return true; } else { return false; } }

int binarySearch(alias pred, T)(in T[] as) { int lo = -1, hi = cast(int)(as.length); for (; lo + 1 < hi; ) { const mid = (lo + hi) >> 1; (unaryFun!pred(as[mid]) ? hi : lo) = mid; } return hi; }
int lowerBound(T)(in T[] as, T val) { return as.binarySearch!(a => (a >= val)); }
int upperBound(T)(in T[] as, T val) { return as.binarySearch!(a => (a > val)); }


enum INF = 10L^^18;

void main() {
  try {
    for (; ; ) {
      const N = readLong;
      const M = readInt;
      const A = readLong;
      const B = readLong;
      auto C = new long[M];
      foreach (i; 0 .. M) {
        C[i] = readLong;
      }
      
      long[] ds;
      for (long d = 1; d * d <= N; ++d) if (N % d == 0) {
        ds ~= d;
        if (d != N / d) ds ~= N / d;
      }
      ds.sort;
      const len = cast(int)(ds.length);
      debug {
        writeln("ds = ", ds);
      }
      
      auto dp = new long[len];
      dp[] = INF;
      dp[0] = -B;
      foreach (j; 0 .. len) {
        long bad = INF;
        foreach (i; 0 .. M) {
          if (C[i] % ds[j] == 0) {
            chmin(bad, C[i]);
          }
        }
        foreach (k; j + 1 .. len) if (ds[k] < bad && ds[k] % ds[j] == 0) {
          const q = ds[k] / ds[j];
          chmin(dp[k], dp[j] + B + A * (q - 1));
        }
      }
      debug {
        writeln("dp = ", dp);
      }
      
      const ans = dp[len - 1];
      writeln((ans >= INF) ? -1 : ans);
    }
  } catch (EOFException e) {
  }
}