记录

#include<bits/stdc++.h>
using namespace std;
long long n,m;
struct room
{
	long long ladder,sum;
}a[10010][110];
long long ans,start;
int main()
{
	freopen("P1076_2.in","r",stdin);
	ios::sync_with_stdio(false);
	cin>>n>>m;
	for(int i=1;i<=n;++i)
	  for(int j=1;j<=m;++j)
	  {
	  	cin>>a[i][j].ladder>>a[i][j].sum;
	  	if(a[i][j].ladder)
	  	  a[i][0].sum++;
	  }
	cin>>start;
	++start;
	for(int i=1;i<=n;++i)
	{
		//cout<<i<<' '<<start<<" "<<a[i][start].sum<<'\n';
		ans+=a[i][start].sum%=20123;
		int num=a[i][start].sum%a[i][0].sum;
		if(num==0)
		  num=a[i][0].sum;
		start--;
		while(num)
		{
			start++;
			if(start>m)
			  start=1;
			num-=a[i][start].ladder;
		}
	}
	cout<<ans%20123;
}