#include<stdio.h>
#include<vector>
#include<math.h>
using namespace std;
typedef long long ll;
typedef double du;
typedef vector<int> vi;
const du eps=1e-5;
template<class t>void gmax(t&a,t b){if(a<b)a=b;
}
ll sqr(ll x){return x*x;}
struct line{ll k,b;int i;line(ll k=0,ll b=0,int i=0):k(k),b(b),i(i){}ll v(ll x){return k*x+b;}
}q[100010],u;
du its(line a,line b){return(b.b-a.b)/(du)(a.k-b.k);
}
int x[100010],y[100010],M;
ll g[100010];
int b[100010];
int get(ll c){int head,tail,i;head=tail=1;q[1]=line((x[1]-1)*-2,sqr(x[1]-1));for(i=1;i<=M;i++){while(head<tail&&its(q[head],q[head+1])<y[i]-eps)head++;if(head<tail&&fabs(its(q[head],q[head+1])-y[i])<eps){b[i]=min(q[head].i,q[head+1].i)+1;head++;}elseb[i]=q[head].i+1;g[i]=q[head].v(y[i])+sqr(y[i])+c-sqr(max(y[i]-x[i+1]+1,0));if(i<M){u=line((x[i+1]-1)*-2,g[i]+sqr(x[i+1]-1),b[i]);while(head<tail&&its(q[tail],q[tail-1])>its(q[tail],u))tail--;q[++tail]=u;}}return b[M];
}
int a[1000010];
ll inter(ll lc,ll rc,ll x){ll lx,ly,rx,ry;lx=get(lc);ly=g[M]-lc*lx;rx=get(rc);ry=g[M]-rc*rx;if(lx!=rx)return(ly-ry)/(rx-lx)*(rx-x)+ry;elsereturn ly;
}
ll take_photos(int n,int m,int k,vi r,vi c){int i,t;ll l,_r,mid,ans;for(i=0;i<n;i++){r[i]++;c[i]++;if(r[i]<c[i])gmax(a[r[i]],c[i]);elsegmax(a[c[i]],r[i]);}M=0;t=0;for(i=1;i<=m;i++){if(a[i]>t){M++;x[M]=i;y[M]=a[i];t=a[i];}}x[M+1]=m+1;k=min(k,M);#define r _rl=0;r=(ll)m*m;ans=0;while(l<=r){mid=(l+r)>>1;if(get(mid)>=k){ans=mid;l=mid+1;}elser=mid-1;}return inter(ans+1,ans,k);#undef r
}