#include<bits/stdc++.h>
using namespace std;
int main(){
	freopen("killer.in","r",stdin);
	freopen("killer.out","w",stdout);
	int m, n, r, a[2147], b[2147];
	cin >> m >> n >> r;
	for(int i = 0; i < m; i++){
		for(int j = 0; j < n; j++){
			cin >> a[i] >> b[j];
			if(b[j]%a[i]==0){
				cout << j+3;
				i--;
				return 0;
			}else{
				if(b[j]%a[i]==0){
					i++;
				}
				if(i >= r){
					cout << j+2;
					return 0; 
				}
			} 
		}
	}
	fclose(stdin);
	fclose(stdout);
	return 0;
}