#include <bits/stdc++.h>
using namespace std;
const long long inf = 1e17;
const int INF = 1e9;
const int N = 1234567;
const string V = " 2017";
struct Node {
  int a[5][5];
  Node() {
    for (int i = 0; i < 5; i++) {
      for (int j = 0; j < 5; j++)
        if (i != j)
          a[i][j] = INF;
        else
          a[i][j] = 0;
    }
  }
  bool OK() {
    for (int i = 0; i < 5; i++)
      for (int j = 0; j < 5; j++)
        if (a[i][j] != (int)1e9) return 0;
    return 1;
  }
};
Node Merge(Node A, Node B) {
  Node C;
  for (int i = 0; i < 5; i++)
    for (int j = 0; j < 5; j++) C.a[i][j] = INF;
  for (int i = 0; i < 5; i++)
    for (int j = 0; j < 5; j++) {
      for (int k = 0; k <= j; k++)
        C.a[i][j] = min(C.a[i][j], A.a[i][k] + B.a[k][j]);
    }
  return C;
}
int n, q;
string s;
Node ans, it[N];
Node operator+(Node x, Node y) {
  Node c = Node();
  for (int i = 0; i < 5; i++) c.a[i][i] = INF;
  for (int i = 0; i < 5; i++) {
    for (int j = 0; j < 5; j++) {
      for (int l = 0; l < 5; l++) {
        c.a[i][j] = min(c.a[i][j], x.a[i][l] + y.a[l][j]);
      }
    }
  }
  return c;
}
void buildit(int k, int l, int r) {
  if (l == r) {
    it[k] = Node();
    if (s[l] == '2') {
      it[k].a[0][0] = 1;
      it[k].a[0][1] = 0;
    } else if (s[l] == '0') {
      it[k].a[1][1] = 1;
      it[k].a[1][2] = 0;
    } else if (s[l] == '1') {
      it[k].a[2][2] = 1;
      it[k].a[2][3] = 0;
    } else if (s[l] == '6') {
      it[k].a[3][3] = 1;
      it[k].a[4][4] = 1;
    } else if (s[l] == '7') {
      it[k].a[3][3] = 1;
      it[k].a[3][4] = 0;
    }
  } else {
    int mid = (l + r) / 2;
    buildit(2 * k, l, mid);
    buildit(2 * k + 1, mid + 1, r);
    it[k] = it[2 * k] + it[2 * k + 1];
  }
}
Node query(int k, int l, int r, int ll, int rr) {
  if (l > rr || ll > r) return Node();
  if (l >= ll && r <= rr) {
    return it[k];
  } else {
    int mid = (l + r) / 2;
    Node res =
        query(2 * k, l, mid, ll, rr) + query(2 * k + 1, mid + 1, r, ll, rr);
    return res;
  }
}
int main() {
  ios ::sync_with_stdio(0);
  cin.tie(0);
  cin >> n >> q >> s;
  s = ' ' + s;
  buildit(1, 1, n);
  for (int i = 0; i < q; i++) {
    int l, r;
    cin >> l >> r;
    Node ans = query(1, 1, n, l, r);
    if (ans.a[0][4] > (r - l + 1)) {
      cout << -1 << endl;
    } else {
      cout << ans.a[0][4] << endl;
    }
  }
  return 0;
}
