#include <stdio.h>
#include <stdlib.h>
#include <math.h>

int main() {
	int n,m;
	double i = 0, a, t;
	int c[100000] = {'0'};
	scanf("%d", &n);
	while (n--) {
		i = 0;
		scanf("%lf%lf", &a, &t);
		while (t--) {
			i = a + i;
			m = (int)(i);
			c[m] = c[m] == 0 ? 1 : 0;
			
		
		}
	}
	for (m = 1; ; m++) {
		if (c[m]==1)
		printf("%d", m);
		break;
	}

	system("pause");
	return 0;
}```