#include <bits/stdc++.h>
using namespace std;
#define all(x) x.begin(), x.end()
#define srtl(x)sort(all(x))
#define srtg(x)sort((x).begin(),(x).end(),greater<>())
#define rev(x) reverse(all(x))
#define lb(x,y) lower_bound(x.begin(),x.end(),y)-x.begin()
#define ub(x,y) upper_bound(x.begin(),x.end(),y)-x.begin()
#define ios ios_base::sync_with_stdio(0);cin.tie(0);cout.tie(0);
#define f first
#define s second
#define pb push_back
#define ins insert
#define next next_permutation
#define _b __builtin_popcount
#define ve vector
#define pii pair<int,int>
#define piii pair<int,pii>
#define vi vector<int>
#define vii vector<pii>
#define viii vector<piii>
#define vvi vector<vi>
#define vs vector<string>
#define vb vector<bool>
#define pV(x)for(auto i:x)cout<<i<<" ";
#define geta(a){for(auto &i:a)cin>>i;}
#define fr(n)for(int i=0;i<n;i++)
#define Fr(n)for(int i=n-1;i>=0;i--)
#define suma(a)accumulate(a.begin(),a.end(),0LL)
#define br(x){cout<<x<<"\n";return;}
#define yesn cout<<"YES\n";
#define yes()br("YES");
#define no(){br("NO")}
#define alice() br("Alice");
#define bob() br("Bob");
#define cn continue;
#define cint const int
#define int long long
int mod=1000000007;
cint mod1=100000007;
cint mod2=998244353;
int ax[8]={0,1,0,-1,-1,1,1,-1};
int ay[8]={1,0,-1,0,1,-1,1,-1};
//bool on(int x,int y){return (x>=0&&x<n&&y>=0&&y<m);}
//int euc(int a,int b,int c,int d){return abs(a-c)+abs(b-d);}
int bp(int x,int y){
if(y==0)return 1;
int r=bp(x,y/2);
return (y&1)?r*r%mod*x%mod:r*r%mod;
}
int bpm(int x,int y){
if(y==0)return 1;
int r=bp(x,y/2);
return (y&1)?r*r*x:r*r;
}
cint N=200006;
int F[N+1],I[N+1];
int cmb(int n,int k){
return (((F[n]*I[k])%mod)*I[n-k])%mod;
}
int cinn(){
int n;
cin>>n;
return n;
}
#define w cinn()
int n,m;
vi a,b;
bool p(int x){
__int128 ap=0;
for(int i=0;i<n;i++){
int c=(x+a[i]-1)/a[i];
if(a[i]*m>=x){
ap+=m-c;
}
else{
c=((x-m*a[i])+b[i]-1)/b[i];
ap-=c;
}
}
return ap>=0;
}
void solve(){
n=w;m=w;
for(int i=0;i<n;i++){
a.pb(w);
}
for(int i=0;i<n;i++){
b.pb(w);
a[i]=max(a[i],b[i]);
}
int mi=-1,ma=(1e9)+10,me;
int res=0;
while(ma-mi!=1){
me=(ma+mi)/2;
if(p(me)){
mi=me;
res=max(res,me);
}
else ma=me;
}
cout<<res;
}
int32_t main(){
ios;
int t=1;
//cin>>t;
/*
F[0]=1;
for(int i=1;i<=N;i++){
F[i]=(i*F[i-1])%mod;
}
I[N]=(bp(F[N],mod-2))%mod;
for(int i=N-1;i>=0;i--){
I[i]=(I[i+1]*(i+1))%mod;
}
//*/
while(t--){
solve();
}
return 0;
}
/*
1 1000000000000000000
1
1
100 1000000000
1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1
1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1
*/
