#include <bits/stdc++.h>
using namespace std;
const int Maxn = 200005;
const int Maxm = 1048576;
const int Maxd = 5;
const int Inf = 1000000000;
struct node {
  int dp[Maxd][Maxd];
  node(int my = -1) {
    for (int i = 0; i < Maxd; i++) {
      for (int j = i + 1; j < Maxd; j++) dp[i][j] = Inf;
      if (my == 2)
        if (i == 0) {
          dp[i][i + 1] = 0;
          dp[i][i] = 1;
        } else
          dp[i][i] = 0;
      else if (my == 0)
        if (i == 1) {
          dp[i][i + 1] = 0;
          dp[i][i] = 1;
        } else
          dp[i][i] = 0;
      else if (my == 1)
        if (i == 2) {
          dp[i][i + 1] = 0;
          dp[i][i] = 1;
        } else
          dp[i][i] = 0;
      else if (my == 7)
        if (i == 3) {
          dp[i][i + 1] = 0;
          dp[i][i] = 1;
        } else
          dp[i][i] = 0;
      else if (my == 6)
        if (i < 3)
          dp[i][i] = 0;
        else
          dp[i][i] = 1;
      else
        dp[i][i] = my == -1 ? Inf : 0;
    }
  }
  node operator+(const node &b) const {
    node c;
    for (int i = 0; i < Maxd; i++)
      for (int j = i; j < Maxd; j++)
        for (int k = j; k < Maxd; k++)
          c.dp[i][k] = min(c.dp[i][k], dp[i][j] + b.dp[j][k]);
    return c;
  }
};
int n, q;
char str[Maxn];
node st[Maxm];
void Create(int v, int l, int r) {
  if (l == r)
    st[v] = node(str[l] - '0');
  else {
    int m = l + r >> 1;
    Create(2 * v, l, m);
    Create(2 * v + 1, m + 1, r);
    st[v] = st[2 * v] + st[2 * v + 1];
  }
}
node Get(int v, int l, int r, int a, int b) {
  if (l == a && r == b)
    return st[v];
  else {
    int m = l + r >> 1;
    if (b <= m) return Get(2 * v, l, m, a, b);
    if (m + 1 <= a) return Get(2 * v + 1, m + 1, r, a, b);
    return Get(2 * v, l, m, a, m) + Get(2 * v + 1, m + 1, r, m + 1, b);
  }
}
int main() {
  scanf("%d %d", &n, &q);
  scanf("%s", str + 1);
  Create(1, 1, n);
  while (q--) {
    int l, r;
    scanf("%d %d", &l, &r);
    int res = Get(1, 1, n, l, r).dp[0][4];
    if (res >= Inf) res = -1;
    printf("%d\n", res);
  }
  return 0;
}
