#include<iostream> using namespace std; int a,b,c,d[112]; int main(){ cin>>a; for(int i=a;i>=1;i=i-1){ cin>>b>>c; d[i]=d[i]+(b+c)%10; if(b+c>9){ d[i+1]=d[i+1]+(b+c)/10; } } if(d[a+1]!=0){ cout<<d[a+1]; } for(int i=a;i>=1;i=i-1){ cout<<d[i]; } return 0; }