#include <bits/stdc++.h>
using namespace std;
string str;
const int NMAX = 200000 + 5;
const int INF = 5 * NMAX;
struct Node {
  int st, dr;
  int cnt[10];
  int ans[5][5];
} tree[4 * NMAX];
void unite(Node &res, const Node a, const Node &b) {
  if (a.st == -1) {
    res = b;
    return;
  }
  for (int i = 0; i < 10; ++i) res.cnt[i] = a.cnt[i] + b.cnt[i];
  for (int i = 0; i < 5; ++i)
    for (int j = i + 1; j < 5; ++j) {
      res.ans[i][j] = INF;
      for (int k = i; k <= j; ++k)
        res.ans[i][j] = min(res.ans[i][j], a.ans[i][k] + b.ans[k][j]);
    }
  res.ans[0][0] = res.cnt[2];
  res.ans[1][1] = res.cnt[0];
  res.ans[2][2] = res.cnt[1];
  res.ans[3][3] = res.cnt[7] + res.cnt[6];
  res.ans[4][4] = res.cnt[6];
}
void build(int node, int st, int dr) {
  tree[node].st = st, tree[node].dr = dr;
  if (st == dr) {
    for (int i = 0; i < 10; ++i) tree[node].cnt[i] = 0;
    tree[node].cnt[str[st] - '0'] = 1;
    for (int i = 0; i < 5; ++i)
      for (int j = i + 1; j < 5; ++j) tree[node].ans[i][j] = INF;
    tree[node].ans[0][0] = tree[node].cnt[2];
    tree[node].ans[1][1] = tree[node].cnt[0];
    tree[node].ans[2][2] = tree[node].cnt[1];
    tree[node].ans[3][3] = tree[node].cnt[7] + tree[node].cnt[6];
    tree[node].ans[4][4] = tree[node].cnt[6];
    if (tree[node].cnt[2] == 1) tree[node].ans[0][1] = 0;
    if (tree[node].cnt[0] == 1) tree[node].ans[1][2] = 0;
    if (tree[node].cnt[1] == 1) tree[node].ans[2][3] = 0;
    if (tree[node].cnt[7] == 1) tree[node].ans[3][4] = 0;
    return;
  }
  int mid = (tree[node].st + tree[node].dr) >> 1;
  build(node << 1, st, mid);
  build((node << 1) + 1, mid + 1, dr);
  unite(tree[node], tree[node << 1], tree[(node << 1) + 1]);
}
Node ans;
void query(int node, int st, int dr) {
  if (tree[node].st == st && tree[node].dr == dr) {
    unite(ans, ans, tree[node]);
    return;
  }
  int mid = (tree[node].st + tree[node].dr) >> 1;
  if (dr <= mid)
    query(node << 1, st, dr);
  else if (st > mid)
    query((node << 1) + 1, st, dr);
  else {
    query(node << 1, st, mid);
    query((node << 1) + 1, mid + 1, dr);
  }
}
int main() {
  ios_base ::sync_with_stdio(false);
  int n, q;
  cin >> n >> q;
  cin >> str;
  str = " " + str;
  build(1, 1, n);
  while (q--) {
    int a, b;
    cin >> a >> b;
    ans.st = -1;
    query(1, a, b);
    if (ans.ans[0][4] == INF)
      cout << "-1\n";
    else
      cout << ans.ans[0][4] << '\n';
  }
  return 0;
}
