样例已过。

蒟蒻代码如下：

# include <bits/stdc++.h>
using namespace std;

int main (){
	int N,M,x,y,a;
	vector<int> v1;
	vector<int> v2;
	cin >> N>> M;
	for (int i=1;i<=N*M;i++){
		cin >> x>> y;
		v1.push_back(x);
		v2.push_back(y);
	}
	cin >> a;
	long long ans=0;
	int j,f=0,t=a,s=t;
	for (int i=1;i<=N;i++){
		ans += v2[M*i+t];
		do{
			++t;
			if (t>M) t=1;
			if (v1[(i-1)*M+t]==1) f++;
		}while(f<=v2[i]);
	}
	cout << ans%20123;
	return 0;
}