#include <bits/stdc++.h>
#pragma comment(linker, "/STACK:512000000")
using namespace std;
void solve(bool);
void precalc();
clock_t start;
int testNumber = 1;
bool todo = true;
int main() {
  start = clock();
  int t = 1;
  cout.sync_with_stdio(0);
  cin.tie(0);
  precalc();
  cout.precision(10);
  cout << fixed;
  int testNum = 1;
  while (t--) {
    solve(true);
    ++testNumber;
  }
  return 0;
}
template <typename T>
T binpow(T q, T w, T mod) {
  if (!w) return 1 % mod;
  if (w & 1) return q * 1LL * binpow(q, w - 1, mod) % mod;
  return binpow(q * 1LL * q % mod, w / 2, mod);
}
template <typename T>
T gcd(T q, T w) {
  while (w) {
    q %= w;
    swap(q, w);
  }
  return q;
}
template <typename T>
T lcm(T q, T w) {
  return q / gcd(q, w) * w;
}
void precalc() {}
const int INF = (int)1e9;
struct Node {
  std::array<std::array<int, 5>, 5> dp;
  Node() {
    for (int i = 0; i < 5; ++i) {
      for (int j = 0; j < 5; ++j) {
        dp[i][j] = INF;
      }
    }
    for (int i = 0; i < 5; ++i) {
      dp[i][i] = 0;
    }
  }
  Node(int num) {
    for (int i = 0; i < 5; ++i) {
      for (int j = 0; j < 5; ++j) {
        dp[i][j] = INF;
      }
    }
    for (int i = 0; i < 5; ++i) {
      dp[i][i] = 0;
    }
    if (num == -1) {
      dp[3][3] = 1;
      dp[4][4] = 1;
    } else if (num < 4) {
      dp[num][num + 1] = 0;
      dp[num][num] = 1;
    }
  }
};
Node merge(const Node& l, const Node& r) {
  Node res;
  for (int i = 0; i < 5; ++i) {
    for (int j = i; j < 5; ++j) {
      res.dp[i][j] = INF;
      for (int x = i; x <= j; ++x) {
        res.dp[i][j] = min(res.dp[i][j], l.dp[i][x] + r.dp[x][j]);
      }
    }
  }
  return res;
}
int shift = 1;
Node tree[2 * (1 << 18) + 5];
Node rmq(int l, int r) {
  if (l >= r) {
    return Node();
  }
  if (l & 1) {
    return merge(tree[l], rmq(l + 1, r));
  }
  if (r & 1) {
    return merge(rmq(l, r - 1), tree[r - 1]);
  }
  return rmq(l / 2, r / 2);
}
Node get_res(int l, int r) { return rmq(l + shift, r + shift); }
void solve(bool read) {
  int n, Q;
  cin >> n >> Q;
  string s;
  cin >> s;
  while (shift < s.length()) {
    shift *= 2;
  }
  for (int i = 0; i < s.length(); ++i) {
    int val;
    switch (s[i]) {
      case '2':
        val = 0;
        break;
      case '0':
        val = 1;
        break;
      case '1':
        val = 2;
        break;
      case '7':
        val = 3;
        break;
      case '6':
        val = -1;
        break;
      default:
        val = 4;
    }
    tree[i + shift] = Node(val);
  }
  for (int i = shift - 1; i > 0; --i) {
    tree[i] = merge(tree[2 * i], tree[2 * i + 1]);
  }
  for (int i = 0; i < Q; ++i) {
    int l, r;
    cin >> l >> r;
    --l;
    Node res = get_res(l, r);
    if (res.dp[0][4] > 1e8) {
      cout << "-1\n";
      continue;
    }
    cout << res.dp[0][4] << "\n";
  }
}
