#include<bits/stdc++.h> using namespace std; long long a[100000],b[100000],c[100000],n; int main() { cin>>n; for (int i=0;i<n;i++) { cin>>a[n-1-i]>>b[n-1-i]; } for (int i=0;i<n;i++) { c[i]+=a[i]+b[i]; c[i+1]+=c[i]/10; c[i]%=10; } while(c[n-1]==0&&n>1) { n--; } for (int i=0;i<n;i++) { cout<<c[n-1-i]; } return 0; }