#include<stdio.h>
#include<stdlib.h>
char a[1000005];
int n;
int run(int i)
{
    int x,y,k;
    if(i>n)return 0;
    scanf("%d%d",&x,&y);
    k=x+y+run(i+1);
    a[i]=k%10+'0';
    return k/10;
}
int main()
{
    scanf("%d",&n);
    a[n+1]=0;
    run(1);
    printf("%s\n",a+1);
    return 0;
}