#include <bits/stdc++.h>
#define rep(i,l,r) for(int i=l;i<=r;++i)
using namespace std;
int n;
int s[424],f[424];
int dfs(int d,int zs,int qs){
int ans=0;
if(d==n+1){
if(zs<0||qs<0) return 0;
return zs+qs;
}
int ans0,ans1;
ans0=dfs(d+1,zs,qs);
ans1=dfs(d+1,zs+s[d],qs+f[d]);
ans=max(ans1,ans0);
return ans;
}
int main()
{
ios::sync_with_stdio(false);
cin>>n;
rep(i,1,n)
cin>>s[i]>>f[i];
cout<<dfs(1,0,0);
}
