#include <bits/stdc++.h>
using namespace std;
const int INF = 1e9;
const int maxn = 200010;
struct node {
  int val[5][5];
  node() {
    for (int i = 0; i < 5; i++) {
      for (int j = 0; j < 5; j++) {
        val[i][j] = INF;
      }
    }
  }
  node operator+(node x) {
    node ans;
    for (int i = 0; i < 5; ++i) {
      for (int j = 0; j < 5; ++j) {
        for (int k = 0; k < 5; ++k) {
          ans.val[i][j] = min(ans.val[i][j], val[i][k] + x.val[k][j]);
        }
      }
    }
    return ans;
  }
} tree[maxn << 2];
int n, q;
char num[maxn];
char ch[] = {'2', '0', '1', '7', '6'};
int Find(char c) {
  for (int i = 0; i < 5; i++) {
    if (ch[i] == c) return i;
  }
  return -1;
}
node push_up(node &a, node &b) {
  node res;
  for (int i = 0; i < 5; i++) {
    for (int j = i; j < 5; j++) {
      for (int k = i; k <= j; k++) {
        res.val[i][j] = min(res.val[i][j], a.val[i][k] + b.val[k][j]);
      }
    }
  }
  return res;
}
void build_tree(int rt, int l, int r) {
  if (l == r) {
    int f = Find(num[l]);
    for (int i = 0; i < 5; i++) {
      tree[rt].val[i][i] = 0;
    }
    if (f != -1 && f < 4) {
      tree[rt].val[f][f + 1] = 0;
      tree[rt].val[f][f] = 1;
    } else if (f == 4) {
      tree[rt].val[3][3] = tree[rt].val[4][4] = 1;
    }
    return;
  }
  int mid = (l + r) >> 1;
  build_tree(rt << 1, l, mid);
  build_tree(rt << 1 | 1, mid + 1, r);
  tree[rt] = push_up(tree[rt << 1], tree[rt << 1 | 1]);
}
node query(int rt, int L, int R, int l, int r) {
  if (l <= L && r >= R) {
    return tree[rt];
  }
  int mid = (L + R) >> 1;
  push_up(tree[2 * rt], tree[2 * rt + 1]);
  node X, Y;
  if (mid < l) return query(2 * rt + 1, mid + 1, R, l, r);
  if (mid >= r) return query(2 * rt, L, mid, l, r);
  return query(2 * rt, L, mid, l, r) + query(2 * rt + 1, mid + 1, R, l, r);
}
int main() {
  cin >> n >> q;
  scanf("%s", num + 1);
  build_tree(1, 1, n);
  while (q--) {
    int l, r;
    scanf("%d %d", &l, &r);
    node ans = query(1, 1, n, l, r);
    if (ans.val[0][4] == INF) {
      ans.val[0][4] = -1;
    }
    printf("%d\n", ans.val[0][4]);
  }
  return 0;
}
