#include<iostream> #include<cmath> #include<cstring> using namespace std; const int maxn = 1e3+5; int n,a[maxn], b[maxn],c[maxn]; bool f; int main() { cin>>n; for(int i=1;i<=n;i++) { cin>>a[n+1-i]>>b[n+1-i]; } for(int i=n;i>=1;i--) { int s=a[i]+b[i]; if(10<=s) { f=true; s=s%10; } else { f=false; } c[i]=c[i]+s; if(f) { c[i+1]=c[i+1]+1; } } if(f) cout << 1; for(int i=n;i>=1;i--) { cout<<c[i]; } return 0; }