#include <bits/stdc++.h>
using namespace std;
int n, m;
char str[200005];
struct Mat {
  int dp[5][5];
  Mat() { memset(dp, 0x3f3f3f3f, sizeof(dp)); }
} A[200005 << 2];
Mat Merge(const Mat &l, const Mat &r) {
  Mat tmp;
  for (int i = (0), i_end_ = (4); i <= i_end_; i++) {
    for (int j = (i), j_end_ = (4); j <= j_end_; j++) {
      for (int k = (j), k_end_ = (4); k <= k_end_; k++) {
        tmp.dp[i][k] = min(tmp.dp[i][k], l.dp[i][j] + r.dp[j][k]);
      }
    }
  }
  return tmp;
}
void build(int L, int R, int p) {
  if (L == R) {
    for (int i = (0), i_end_ = (4); i <= i_end_; i++) A[p].dp[i][i] = 0;
    if (str[L] == '2') {
      A[p].dp[0][1] = 0;
      A[p].dp[0][0] = 1;
    }
    if (str[L] == '0') {
      A[p].dp[1][2] = 0;
      A[p].dp[1][1] = 1;
    }
    if (str[L] == '1') {
      A[p].dp[2][3] = 0;
      A[p].dp[2][2] = 1;
    }
    if (str[L] == '7') {
      A[p].dp[3][4] = 0;
      A[p].dp[3][3] = 1;
    }
    if (str[L] == '6') {
      A[p].dp[3][3] = 1;
      A[p].dp[4][4] = 1;
    }
    return;
  }
  int mid = (L + R) >> 1;
  build(L, mid, p << 1);
  build(mid + 1, R, p << 1 | 1);
  A[p] = Merge(A[p << 1], A[p << 1 | 1]);
}
Mat query(int L, int R, int p, int l, int r) {
  if (L == l && R == r) return A[p];
  int mid = (L + R) >> 1;
  if (r <= mid)
    return query(L, mid, p << 1, l, r);
  else if (l > mid)
    return query(mid + 1, R, p << 1 | 1, l, r);
  else
    return Merge(query(L, mid, p << 1, l, mid),
                 query(mid + 1, R, p << 1 | 1, mid + 1, r));
}
int main() {
  scanf("%d%d%s", &n, &m, str + 1);
  build(1, n, 1);
  for (int i = (1), i_end_ = (m); i <= i_end_; i++) {
    int L, R;
    scanf("%d%d", &L, &R);
    Mat res = query(1, n, 1, L, R);
    printf("%d\n", res.dp[0][4] == 0x3f3f3f3f ? -1 : res.dp[0][4]);
  }
  return 0;
}
