#include <bits/stdc++.h>

using namespace std;

ifstream fin("aliens.in");
ofstream fout("aliens.out");

const int l3 = 18 * 50 + 30, l5 = 12 * 50 + 30;

short int dp[2][l3 + l3 + 5][l5 + l5 + 5], inf = -30000, p, q, u, v;

double best = -1;

int main()
{
    for (int i = 0; i <= l3 + l3; ++i)
    {
        for (int j = 0; j <= l5 + l5; ++j)
        {
            dp[0][i][j] = inf;
        }
    }
    dp[0][l3][l5] = 0;
    int n;
    fin >> n;
    for (int i = 1; i <= n; ++i)
    {
        int x, y;
        short int p2 = 0, p3 = 0, p5 = 0;
        fin >> x >> y;

        while (x % 2 == 0) x /= 2, ++p2;
        while (x % 3 == 0) x /= 3, ++p3;
        while (x % 5 == 0) x /= 5, ++p5;

        while (y % 2 == 0) y /= 2, --p2;
        while (y % 3 == 0) y /= 3, --p3;
        while (y % 5 == 0) y /= 5, --p5;

        if (p3 >= 0) p += p3;
        else q += p3;
        if (p5 >= 0) u += p5;
        else v += p5;

        for (int j = q; j <= p; ++j)
        {
            for (int k = u; k <= v; ++k)
            {
                dp[i % 2][j + l3][k + l3] = inf;
                if (dp[1 - i % 2][j + l3][k + l3] > dp[i % 2][j + l3][k + l3])
                {
                    dp[i % 2][j + l3][k + l3] = dp[1 - i % 2][j + l3][k + l3];
                }
                if (p2 + dp[1 - i % 2][j - p3 + l3][k - p5 + l5] > dp[i % 2][j + l3][k + l3])
                {
                    dp[i % 2][j + l3][k + l3] = p2 + dp[1 - i % 2][j - p3 + l3][k - p5 + l5];
                }
            }
        }
    }
    fin.close();
    fout.close();
    return 0;
}