#include <fstream>

#define I_F "light.in"
#define O_F "light.out"
#define MAX 20000000

using namespace std;

bool f[MAX];

void Input();
void Output();

int main()
{
	Input();
	Output();
	return 0;
}

void Input()
{
	int n,i;
	long j,t;
	double a;
	ifstream fin(I_F);
	fin>>n;
	for (i=0; i<n; i++)
	{
		fin>>a>>t;
		for (j=1; (j<=t)&&(a*j<=MAX); j++)
			f[(int)(a*(double)j)]=!f[(int)(a*(double)j)];
	}
	fin.close();
}

void Output()
{
	ofstream fout(O_F);
	for (long i=1; i<MAX; i++)
		if (f[i])
		{
			fout<<i<<'\n';
			break;
		}
	fout.close();
}