day1

include

using namespace std;

int main() {
int n,t;
double a;
int l[5000];
for (int i = 1; i < 5000; i++) {
l[i] = 0;
}
cin >> n;
for (int i = 0; i < n; i++) {
cin >> a >> t;
for (int j = 1; j <= t; j++)
l[(int)(a * j) ] = !l[(int)(a * j)];
}
int m = 1;
while (l[m] == 0)
m++;
cout << m << endl;
return 0;
}