#include <bits/stdc++.h>
using namespace std;
long long int power(long long int a, long long int b) {
  if (b == 0) return 1;
  if (b == 1) return a;
  long long int r = power(a, b / 2) % 1000000007;
  if (b % 2 == 0)
    return (r * r) % 1000000007;
  else
    return (((r * r) % 1000000007) * a) % 1000000007;
}
int prime[1000009];
int sumprime[1000009];
void sieve(int n) {
  prime[0] = prime[1] = 1;
  for (int i = 2; i <= sqrt(n); i++) {
    if (!prime[i]) {
      for (int j = 2 * i; j <= n; j = j + i) {
        prime[j]++;
      }
    }
  }
  for (int i = 1; i <= n; i++) {
    if (!prime[i]) {
      sumprime[i] = sumprime[i - 1] + 1;
    } else {
      sumprime[i] = sumprime[i - 1];
    }
  }
}
bool comp(const pair<long long int, long long int> &a,
          const pair<long long int, long long int> &b) {
  return (a.second < b.second);
}
const int N = 5 * 1e5 + 9;
int main() {
  ios_base::sync_with_stdio(false);
  cin.tie(NULL);
  cout.tie(NULL);
  int n;
  cin >> n;
  string s;
  cin >> s;
  int a[n], b[n];
  for (int i = 0; i < n; i++) {
    cin >> a[i] >> b[i];
  }
  map<long long int, long long int> mp;
  for (int i = 0; i < n; i++) {
    for (int j = 0; j < 10000; j++) {
      if (j - b[i] >= 0 && (j - b[i]) % a[i] == 0) {
        if (s[i] == '1') {
          s[i] = '0';
        } else {
          s[i] = '1';
        }
      }
      if (s[i] == '1') {
        mp[j]++;
      }
    }
  }
  long long int ma = 0;
  for (auto it : mp) {
    ma = max(ma, it.second);
  }
  cout << ma << "\n";
  return 0;
}
