#include <bits/stdc++.h> #include <ext/pb_ds/assoc_container.hpp> #include <ext/pb_ds/tree_policy.hpp> using namespace std; typedef long long ll; typedef pair<int,int> P; typedef pair<int,P> P1; typedef pair<P,P> P2; #define pu push #define pb push_back #define mp make_pair #define eps 1e-7 #define INF 1000000000 #define mod 1000000007 #define fi first #define sc second #define rep(i,x) for(int i=0;i<x;i++) #define repn(i,x) for(int i=1;i<=x;i++) #define SORT(x) sort(x.begin(),x.end()) #define ERASE(x) x.erase(unique(x.begin(),x.end()),x.end()) #define POSL(x,v) (lower_bound(x.begin(),x.end(),v)-x.begin()) #define POSU(x,v) (upper_bound(x.begin(),x.end(),v)-x.begin()) #include <bits/stdc++.h> #include <ext/pb_ds/assoc_container.hpp> #include <ext/pb_ds/tree_policy.hpp> using namespace std; typedef long long ll; typedef pair<int,int> P; typedef pair<int,P> P1; typedef pair<P,P> P2; #define pu push #define pb push_back #define mp make_pair #define eps 1e-7 #define INF 1000000000 #define mod 1000000007 #define fi first #define sc second #define rep(i,x) for(int i=0;i<x;i++) #define repn(i,x) for(int i=1;i<=x;i++) #define SORT(x) sort(x.begin(),x.end()) #define ERASE(x) x.erase(unique(x.begin(),x.end()),x.end()) #define POSL(x,v) (lower_bound(x.begin(),x.end(),v)-x.begin()) #define POSU(x,v) (upper_bound(x.begin(),x.end(),v)-x.begin()) int n; int a[55],b[55],dif,sum,mx,ans; int main(){ cin >> n; rep(i,n-1){ cin >> a[i] >> b[i]; dif += a[i]-b[i]; sum += a[i]+b[i]; mx = max(mx,a[i]+b[i]); } for(int x=0;x<=2000000;x++){ int y = x+dif; if(y < 0) continue; if(mx*2 > sum+x+y || (x+y)*2 > sum+x+y) continue; ans++; } cout << ans << endl; }