#include<iostream> #include<cstring> #include<cstdio> #include<algorithm> #include<cstdlib> using namespace std; const int maxn = 100010; int n; struct node{ int w,s; }floor[maxn]; int cmp(node a,node b){ return a.w-b.s < b.w - a.s; } int main() { //if(freopen("input.txt","r",stdin)== NULL) {printf("Error\n"); exit(0);} while(scanf("%d",&n) != EOF){ for(int i=0;i<n;i++) scanf("%d%d",&floor[i].w,&floor[i].s); sort(floor,floor+n,cmp); long long int ans = 0; long long int sum = 0; for(int i=0;i<n;i++){ ans = max(ans,sum-floor[i].s); sum += floor[i].w; } if(ans < 0) printf("0\n"); else printf("%I64d\n",ans); } return 0; }