import std.stdio, std.array, std.string, std.conv, std.algorithm; import std.typecons, std.range, std.random, std.math, std.container; import std.numeric, std.bigint, core.bitop, core.stdc.string; bool miller_rabin(BigInt n, int k = 10) { if (n % 2 == 0) return false; BigInt d = n - 1; BigInt s = 0; while (d % 2) { s += 1; d /= 2; } while (k--) { BigInt a = uniform(0L, n.to!long).to!BigInt; if (powmod(a, d, n) == 1) continue; bool composite = true; BigInt r = 1; while (s--) { if (powmod(a, r * d, n) == n - 1) { composite = false; break; } r *= 2; } if (composite) return false; } return true; } void main() { auto N = readln.chomp.to!int; auto A = readln.split.map!(to!int).array; A.sort(); BigInt ans = -1; do { BigInt n = A.map!(to!string).join("").to!BigInt; if (n <= ans) continue; if (miller_rabin(n)) ans = max(ans, n); } while (nextPermutation(A)); ans.writeln; } BigInt powmod(BigInt a, BigInt x, BigInt m) { BigInt ret = 1; while (x) { if (x % 2) ret = ret * a % m; a = a * a % m; x /= 2; } return ret; }