#include<iostream> using namespace std; int a[110]; int main(){ int n,x,y; cin>>n; for(int i = 0; i < n; i++){ cin>>x>>y; a[n-i-1] += x+y; if(a[n-i-1] >= 10){ a[n-i] += a[n-i-1]/10; a[n-i-1] %= 10; } } if(a[n+1]){ n++; } for(int i = n-1; i >= 0; i--){ cout<<a[i]; } return 0; }