#include <bits/stdc++.h>
using namespace std;
template <class T>
inline bool chkmin(T &x, T y) {
  return y < x ? x = y, 1 : 0;
}
template <class T>
inline bool chkmax(T &x, T y) {
  return x < y ? x = y, 1 : 0;
}
inline long long Max(long long x, long long y) { return x > y ? x : y; }
inline long long Min(long long x, long long y) { return x < y ? x : y; }
int n, m;
char s[200002];
struct mat {
  int a[6][6];
  mat() { memset(a, 0, sizeof(a)); }
  void init() {
    for (int i = (0), i_end_ = (4); i <= i_end_; i++)
      for (int j = (0), j_end_ = (4); j <= j_end_; j++)
        a[i][j] = i == j ? 0 : 0x3f3f3f3f;
  }
  mat operator+(const mat &b) const {
    mat res;
    memset(res.a, 0x3f3f3f3f, sizeof(res.a));
    for (int i = (0), i_end_ = (4); i <= i_end_; i++)
      for (int j = (0), j_end_ = (4); j <= j_end_; j++)
        for (int k = (0), k_end_ = (4); k <= k_end_; k++)
          chkmin(res.a[i][j], a[i][k] + b.a[k][j]);
    return res;
  }
  void Pr() {
    for (int i = (0), i_end_ = (4); i <= i_end_; i++)
      for (int j = (0), j_end_ = (4); j <= j_end_; j++)
        printf("%d%c", a[i][j], j < 4 ? ' ' : '\n');
  }
};
struct Tree {
  struct node {
    int L, R;
    mat sum;
  } tree[200002 << 2];
  void Up(node &A, node &L, node &R) { A.sum = L.sum + R.sum; }
  void build(int L, int R, int p) {
    tree[p].L = L, tree[p].R = R;
    if (L == R) {
      tree[p].sum.init();
      if (s[L] == '2') tree[p].sum.a[0][0] = 1, tree[p].sum.a[0][1] = 0;
      if (s[L] == '0') tree[p].sum.a[1][1] = 1, tree[p].sum.a[1][2] = 0;
      if (s[L] == '1') tree[p].sum.a[2][2] = 1, tree[p].sum.a[2][3] = 0;
      if (s[L] == '7') tree[p].sum.a[3][3] = 1, tree[p].sum.a[3][4] = 0;
      if (s[L] == '6') tree[p].sum.a[3][3] = 1, tree[p].sum.a[4][4] = 1;
      return;
    }
    int mid = (L + R) >> 1;
    build(L, mid, p << 1), build(mid + 1, R, p << 1 | 1);
    Up(tree[p], tree[p << 1], tree[p << 1 | 1]);
  }
  mat query(int L, int R, int p) {
    if (tree[p].L == L && tree[p].R == R) return tree[p].sum;
    int mid = (tree[p].L + tree[p].R) >> 1;
    if (R <= mid)
      return query(L, R, p << 1);
    else if (L > mid)
      return query(L, R, p << 1 | 1);
    else
      return query(L, mid, p << 1) + query(mid + 1, R, p << 1 | 1);
  }
} T;
int main() {
  scanf("%d%d", &n, &m);
  scanf("%s", s + 1);
  T.build(1, n, 1);
  while (m--) {
    int l, r;
    scanf("%d%d", &l, &r);
    mat ans = T.query(l, r, 1);
    printf("%d\n", ans.a[0][4] == 0x3f3f3f3f ? -1 : ans.a[0][4]);
  }
  return 0;
}
