#include <bits/stdc++.h>
#pragma GCC optimize("O3")
using namespace std;
#define ll long long
ll mod = 998244353;
//mt19937 rng(chrono::steady_clock::now().time_since_epoch().count());
ll binpow(ll a, ll b)
{
ll res = 1;
while (b>0)
{
if (b&1)
res = (res*a)%mod;
a = (a*a)%mod;
b>>=1;
}
return res;
}
ll gcd(ll x, ll y)
{
if (y==0)
return x;
return gcd(y, x%y);
}
void solve()
{
ll n;
cin>>n;
vector<ll>v(n+1, 0);
ll a = 0, b = 0;
vector<ll>va(n+1), vb(n+1);
for (int i=1 ; i<=n ; i++)
{
ll x,y;
cin>>x>>y;
va[i] = x;
vb[i] = y;
a += x;
b += y;
v[i] = y-x;
}
vector<ll>pref(n+1, 0);
for (int i=1 ; i<=n ;i++) pref[i] = v[i]+pref[i-1];
ll res = 0;
for (int i=1 ; i<=n ; i++)
{
res += abs(pref[i]);
}
if (a==b)
cout<<res<<endl;
else
{
vector<ll>sn(n+1, 0), sp(n+1, 0);
if (pref[n]>=0) sp[n] = 1; else sn[n] = 1;
for (int i=n-1 ; i>=1 ; i--)
{
if (pref[i]>=0) sp[i] = 1; else sn[i] = 1;
sp[i] += sp[i+1];
sn[i] += sn[i+1];
}
ll ans = res;
for (int i=1 ; i<=n ;i++)
{
if (va[i]>0)
{
ans = min(ans, res+sp[i]-sn[i]);
}
}
cout<<ans<<endl;
}
}
int main()
{
ios_base::sync_with_stdio(false);
cin.tie(nullptr);
ll tt = 1;
// cin>>tt;
while (tt--)
{
solve();
}
return 0;
}
