/* -*- coding: utf-8 -*-
 *
 * 904.cc:  No.904 サメトロ - yukicoder
 */

#include<cstdio>
#include<cstdlib>
#include<cstring>
#include<cmath>
#include<iostream>
#include<string>
#include<vector>
#include<map>
#include<set>
#include<stack>
#include<list>
#include<queue>
#include<deque>
#include<algorithm>
#include<numeric>
#include<utility>
#include<complex>
#include<functional>
 
using namespace std;

/* constant */

const int MAX_N = 37;

/* typedef */

/* global variables */

int as[MAX_N], bs[MAX_N];

/* subroutines */

inline void setmax(int &a, int b) { if (a < b) a = b; }

/* main */

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

  int asum = 0, bsum = 0;
  for (int i = 0; i < n; i++) {
    scanf("%d%d", as + i, bs + i);
    asum += as[i], bsum += bs[i];
  }
  //printf("asum=%d, bsum=%d\n", asum, bsum);

  int mina = max(0, bsum - asum), minb = max(0, asum - bsum);
  for (int i = 0; i < n; i++) {
    setmax(mina, bs[i] - (asum - as[i]));
    setmax(minb, as[i] - (bsum - bs[i]));
  }

  int da = bsum - mina + 1, db = asum - minb + 1;
  //printf("da=%d, db=%d\n", da, db);

  printf("%d\n", min(da, db));
  return 0;
}