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