#include <bits/stdc++.h> #define int long long #define debug cout << "ok\n"; #define SQR(x) (1LL * ((x) * (x))) #define MASK(i) (1LL << (i)) #define BIT(x, i) (((x) >> (i)) & 1) #define fi first #define se second #define pb push_back #define mp make_pair #define pii pair<int,int> #define pli pair<ll,int> #define vi vector<int> #define FAST ios_base::sync_with_stdio(0);cin.tie(0);cout.tie(0); typedef long long ll; typedef unsigned long long ull; typedef long double ld; typedef unsigned int ui; using namespace std; const int M = 1e9 + 7; const int INF = 1e9 + 7; const ll INFLL = (ll)2e18 + 7LL; const ld PI = acos(-1); const int dx[] = {1, -1, 0, 0, -1, 1, 1, -1}; const int dy[] = {0, 0, 1, -1, -1, -1, 1, 1}; template<class _, class __> bool minimize(_ &x, const __ y){ if(x > y){ x = y; return true; } else return false; } template<class _, class __> bool maximize(_ &x, const __ y){ if(x < y){ x = y; return true; } else return false; } template<class _,class __> void Add(_ &x, const __ y) { x += y; if (x >= M) { x -= M; } return; } template<class _,class __> void Diff(_ &x, const __ y) { x -= y; if (x < 0) { x += M; } return; } //-------------------------------------------------------------- const int MaxN = 1e6+7; int n,m,a[MaxN],b[MaxN],res = 0; bool check(int ans) { int tmp = 0; for (int i=1;i<=n;i++) { if (a[i] * m >= ans) { tmp += m - ((ans-1)/a[i] + 1); } else tmp -= (ans - a[i] * m - 1) / b[i] + 1; } return tmp >= 0; } void sol() { cin >> n >> m; for (int i=1;i<=n;i++) cin >> a[i]; for (int i=1;i<=n;i++) cin >> b[i]; for (int i=1;i<=n;i++) maximize(a[i],b[i]); int l = 1,r = 1e18; while (l <= r) { int mid = (l+r) >>1 ; if (check(mid)) { res = mid; l = mid + 1; } else r = mid - 1; } cout << res; } signed main() { // freopen("test.inp","r",stdin); // freopen("test.out","w",stdout); FAST int t=1; // cin >> t; while (t--) sol(); }