#include <bits/stdc++.h>
#pragma GCC optimize("-O3")
using namespace std;
const long long N = 1e5 + 5;
void pairsort(long long a[], long long b[], long long n) {
  pair<long long, long long> pairt[n];
  for (long long i = 0; i < n; i++) {
    pairt[i].first = a[i];
    pairt[i].second = b[i];
  }
  sort(pairt, pairt + n);
  for (long long i = 0; i < n; i++) {
    a[i] = pairt[i].first;
    b[i] = pairt[i].second;
  }
}
long long gcd(long long a, long long b) {
  if (b == 0) return a;
  return gcd(b, a % b);
}
long long isPrime(long long n) {
  if (n < 2) return 0;
  if (n < 4) return 1;
  if (n % 2 == 0 or n % 3 == 0) return 0;
  for (long long i = 5; i * i <= n; i += 6)
    if (n % i == 0 or n % (i + 2) == 0) return 0;
  return 1;
}
long long C(long long n, long long r) {
  if (r > n - r) r = n - r;
  long long ans = 1;
  for (long long i = 1; i <= r; i++) {
    ans *= n - r + i;
    ans /= i;
  }
  return ans;
}
long long mod = 1e9 + 7;
long long modexpo(long long x, long long p) {
  long long res = 1;
  x = x % mod;
  while (p) {
    if (p % 2) res = res * x;
    p >>= 1;
    x = x * x % mod;
    res %= mod;
  }
  return res;
}
long long n, a[105], b[105], M[N], ans;
string s;
int32_t main() {
  ios::sync_with_stdio(0);
  cin.tie(0);
  cout.tie(0);
  ;
  cin >> n >> s;
  for (long long i = 1; i <= n; i++) cin >> a[i] >> b[i];
  for (long long i = 1; i <= n; i++) {
    long long x = s[i - 1] - '0';
    M[0] += x;
    for (long long j = 0; j <= (1e5 - b[i]) / a[i]; j++) {
      if (!x)
        M[j * a[i] + b[i]]++;
      else
        M[j * a[i] + b[i]]--;
      x ^= 1;
    }
  }
  ans = M[0];
  for (long long i = 1; i <= 1e5; i++)
    M[i] += M[i - 1], ans = (M[i] > ans ? M[i] : ans);
  cout << ans;
  return 0;
}
