/*input
3
1 1
1 2
2 1
*/
#include <bits/stdc++.h>
#include <ext/pb_ds/assoc_container.hpp>
using namespace std;
using namespace __gnu_pbds;
#define REP(i,j,k)     for(int i = j ; i < k ; ++i)
#define RREP(i,j,k)    for(int i = j ; i >=k ; --i)
#define A    first
#define B    second
#define mp   make_pair
#define pb   emplace_back
#define PII pair<int , int>
#define MEM(i,j)   memset(i , j , sizeof i)
#define ALL(i)     i.begin() , i.end()
#define DBGG(i,j)     cout << i << " " << j << endl
#define DB4(i,j,k,l)  cout << i << " " << j << " " << k << " " << l << endl
#define IOS cin.tie() , cout.sync_with_stdio(0)
#define endl "\n"
///------------------------------------------------------------
#define MAX 220
#define INF 0x3f3f3f3f

int lx[MAX] , ly[MAX] , good[MAX] , w[MAX][MAX] , slk[MAX];
int n , s[MAX] , t[MAX];
PII x[MAX];
int match(int now){
	s[now] = 1;
	REP(to , 0 , n){
		if(t[to]) continue;
		if(lx[now] + ly[to] == w[now][to]){
			t[to] = 1;
			if(good[to] == -1 || match(good[to]))
				return good[to] = now , 1;
		}
		else slk[to] = min(slk[to] , lx[now] + ly[to] - w[now][to]);
	}
	return 0;
}
void update(){
	int val = INF;
	REP(i , 0 , n) if(t[i] == 0) val = min(val , slk[i]);
	REP(i , 0 , n){
		if(s[i]) lx[i] -= val;
		if(t[i]) ly[i] += val;
	}
}
void solve(){
	REP(i , 0 , n){
		REP(j , 0 , n){
			good[i] = -1;
			lx[i] = max(lx[i] , w[i][j]);
		}
	}
	REP(i , 0 , n){
		MEM(slk , INF);
		while(1){
			MEM(s , 0) , MEM(t , 0);
			if(match(i)) break;
			else update();
		}
	}
}
int32_t main(){
	cin >> n;
	REP(i , 0 , n) cin >> x[i].A >> x[i].B;
	REP(i , 0 , n){
		REP(j , 0 , n){
			if(x[i] == x[j] && i > j) w[i][j] = x[j].A * x[j].B;
			if(x[i] != x[j] && x[i].A >= x[j].A && x[i].B >= x[j].B)
				w[i][j] = x[j].A * x[j].B;
		}
	}
	solve();
	int ans = 0;
	REP(i , 0 , n) ans += x[i].A * x[i].B - w[good[i]][i];
	cout << ans << endl;
    return 0;
}