#include <bits/stdc++.h>
#define coutf(n, m) cout << fixed << setprecision(n) << m
#define forr(i, a, n) for (int i = a; i < n; i++)
#define forl(i, a, n) for (int i = a; i > n; i--)
#define macos ios::sync_with_stdio(0);cin.tie(0);cout.tie(0)
#define endll "\n"
#define sp " "
typedef long long ll;
using namespace std;
ll n,sum,ans,mx;
vector<pair<ll,ll>> art;
int main(){macos;
cin >> n;
art.resize(n);
for(auto &[a,b]:art)cin >> a >> b,sum += b;
sort(art.rbegin(),art.rend());
ans = mx = sum - art[0].first + art[n-1].first;
forr(i,0,n-1){
auto [a,b] = art[i];
// if(a-b-art[i+1].first<0)break;
ans += a - b - art[i+1].first;
mx = max(mx,ans);
}
cout << mx;
return 0;
}
