#include "stdio.h"
int total[1000000];
int main()
{
      long N,i;
      int a,b;
      scanf("%ld",&N);
	for(i=0;i<N;i++)
	{
            scanf("%d %d",&a,&b);
		total[i]=a+b;
	}
	for(i=N-1;i>0;i--)
	{
		total[i-1]+=total[i]/10;
		total[i]=total[i]%10;
	}
	for(i=0;i<N;i++) printf("%d",total[i]);
      printf("\n");
}