#include<bits/stdc++.h>
using namespace std;
// #define DEBUG 1
// #define COMPILE 1
typedef long long ll;
typedef pair<ll,ll> ii;
#define db(x) cout<<#x<<" = "<<x<<"\n";
#define fore(i,a,b) for(ll i=a,ggdem=b;i<ggdem;i++)
#define FIN ios::sync_with_stdio(false);cin.tie(0);cout.tie(0)
#define SZ(a) ((ll)(a).size())
#define ALL(a) a.begin(),a.end()
#define mset(a,b) memset(a,b,sizeof(a));
#define pb push_back
#define fst first
#define snd second
mt19937 rng(chrono::steady_clock::now().time_since_epoch().count());
const ll INF=1e15;
ll n,m,k,dp[1024][1024],wh[1024];
vector<ii>v;
ll sq(ll x){return x*x;}
bool in(ii a,ii b) { // a inside b
return b.fst<=a.fst && a.snd<=b.snd;
}
ll cost(ll l,ll r,ll mid) { // [l,r] - [m,r]
ll res=0;
if (l<=mid && mid<=r)res=sq(r-l+1) - sq(r-mid+1);
else res=sq(r-l+1);
#ifdef DEBUG
cout<<"["<<l<<","<<r<<"] - ["<<mid<<","<<r<<"]: "<<res<<endl;
#endif
return res;
}
bool compare(const ii &a,const ii &b) {
return a.fst<b.fst || (a.fst==b.fst && a.snd>b.snd);
}
ll solve(int i,int j) {
if(i==n)return 0;
if(dp[i][j]!=-1)return dp[i][j];
ll res=INF;
if(j==k-1) {
res=cost(v[i].fst,v[n-1].snd,v[n].fst)+solve(n,j);
} else {
ll to=-1;
fore(k,i,n) {
to=max(to,v[k].snd);
#ifdef DEBUG
cout<<i<<","<<j<<" to "<<k<<" : "<<cost(v[i].fst,to,v[k+1].fst)<<"+"<<solve(k+1,j+1)<<" | "<<v[i].fst<<" "<<to<<" "<<v[k+1].fst<<endl;
#endif
res=min(res,cost(v[i].fst,to,v[k+1].fst) + solve(k+1,j+1));
}
}
return dp[i][j]=res;
}
vector<ii> get(vector<int> &r,vector<int> &c) {
vector<ii>v;
fore(i,0,SZ(r)){
if(r[i]<=c[i])v.pb({r[i],c[i]});
else v.pb({c[i],r[i]});
}
sort(ALL(v),compare);
vector<ii>res;
for(auto it:v) {
if(!SZ(res) || !in(it,res.back()))res.pb(it);
}
return res;
}
ll take_photos(int _n,int _m,int _k,vector<int>r,vector<int> c) {
n=_n,m=_m,k=_k;
v=get(r,c);
n=SZ(v);
v.pb({INF,INF});
#ifdef DEBUG
cout<<"v: "<<endl;for(auto it:v)cout<<it.fst<<" "<<it.snd<<endl;cout<<"n: "<<n<<endl;
#endif
memset(dp,-1,sizeof(dp));
return solve(0,0);
}
#ifdef COMPILE
int main() {FIN;
int n,m,k;
cin>>n>>m>>k;
vector<int>r(n),c(n);
fore(i,0,n)cin>>r[i]>>c[i];
cout<<take_photos(n,m,k,r,c)<<"\n";
}
#endif
/*
5 7 2
0 3
4 4
4 6
4 5
4 6
---> 25
2 5 2
1 4
4 1
---> 16
5 6 4
1 6
1 3
2 4
3 3
5 1
--> 4
*/
