#include<bits/stdc++.h>
using namespace std;
#define int long long 
int n,a[100004],b[100005],x,y,num=0;
signed main(){
	cin>>n>>x>>y;
	num=x;
	for(int i=0;i<n;i++){
		if(num>=y){
			cout<<num;
			return 0;
		}
		cin>>a[i]>>b[i];
		if(num<a[i]){
			cout<<num;
			return 0;
		}else{
		num-=a[i];
		num+=b[i];
		}
	}
	cout<<num;
}