#include <bits/stdc++.h>
using namespace std;
int get(int n, int p) {
  int res = 0;
  while (n >= p) res += n / p, n /= p;
  return res;
}
template <class T>
T power(T N, T P) {
  return (P == 0) ? 1 : N * power(N, P - 1);
}
void VC(vector<long long int>& v) {
  for (int i = 0; i < v.size(); i++) printf("%lld ", v[i]);
  printf("\n");
}
template <typename T>
void print(const T& v) {
  cerr << v << ' ';
}
template <typename T1, typename... T2>
void print(const T1& first, const T2&... rest) {
  print(first);
  print(rest...);
}
long long BigMod(long long int a, long long int b, int M) {
  long long remainder, answer = 1;
  remainder = a % M;
  while (b != 0) {
    if (b % 2 == 1) answer = (answer * remainder) % M;
    remainder = (remainder * remainder) % M;
    b /= 2;
  }
  return answer;
}
bool cmp(int a, int b) { return a > b; }
int cnt[102][1005] = {0};
int main() {
  int n, dd;
  scanf("%d", &(n));
  string s;
  cin >> s;
  int a[n + 4], start[n + 4];
  for (int i = 0; i < n; i++) {
    scanf("%d", &(a[i]));
    scanf("%d", &(start[i]));
  }
  for (int i = 0; i < n; i++) {
    cnt[i][0] = ((s[i] == '1') ? 1 : 0);
  }
  for (int i = 0; i < n; i++) {
    if (s[i] == '1') {
      for (int j = 0; j < start[i]; j++) {
        cnt[i][j] = 1;
      }
      start[i] += a[i];
    } else {
      for (int j = 0; j < start[i]; j++) {
        cnt[i][j] = 0;
      }
    }
  }
  for (int i = 0; i < n; i++) {
    dd = 1;
    for (int j = start[i]; j <= 1e3; j++, dd++) {
      cnt[i][j] = 1;
      if (dd % a[i] == 0) {
        j += a[i];
      }
    }
  }
  long long int mxx = 0, sum;
  for (int i = 0; i < 1e3; i++) {
    sum = 0;
    for (int j = 0; j < n; j++) {
      sum += cnt[j][i];
    }
    mxx = max(mxx, sum);
  }
  cout << mxx;
  return 0;
}
