#include<bits/stdc++.h>
using namespace std;

const int N = 505;

int mnx[N][N], mny[N][N];
int x[N], y[N];
long long f[N][N];

int main(){
    int n;
    scanf("%d", &n);

    for(int i = 1; i <= n; i ++)scanf("%d%d", &x[i], &y[i]);

    for(int i = 1; i <= n; i ++){
        mnx[i][i] = x[i], mny[i][i] = y[i];
        for(int j = i + 1; j <= n; j ++){
            mnx[i][j] = min(mnx[i][j - 1], x[j]);
            mny[i][j] = min(mny[i][j - 1], y[j]);
        }
    }

    for(int l = n; l >= 1; l --){
        f[l][l] = x[l] + y[l];
        for(int r = l + 1; r <= n; r ++){
            f[l][r] = 2e18;
            for(int k = 1; k < r; k ++){
                f[l][r] = min(f[l][r], f[l][k] + f[k + 1][r]);
            }
            f[l][r] -= mnx[l][r] + mny[l][r];
        }
    }

    printf("%lld\n", f[1][n]);
    return 0;
}