#include <bits/stdc++.h>
using namespace std;
int n, q;
char wcz[1000007];
int tab[1000007];
int n1;
int inf = 1000000;
int drzewo[530000][5][5];
int sta[5];
int now[5];
int potenga(int v) {
  for (int i = 1; 1; i <<= 1)
    if (i >= v) return i;
}
void start(int v, int a, int b) {
  for (int i = 0; i <= 4; i++)
    for (int j = 0; j <= 4; j++) drzewo[v][i][j] = inf;
  if (a == b) {
    if (!tab[a]) {
      for (int i = 0; i <= 4; i++) drzewo[v][i][i] = 0;
    }
    if (tab[a] == 1) {
      for (int i = 0; i <= 4; i++) drzewo[v][i][i] = 0;
      drzewo[v][0][0] = 1;
      drzewo[v][0][1] = 0;
    }
    if (tab[a] == 2) {
      for (int i = 0; i <= 4; i++) drzewo[v][i][i] = 0;
      drzewo[v][1][1] = 1;
      drzewo[v][1][2] = 0;
    }
    if (tab[a] == 3) {
      for (int i = 0; i <= 4; i++) drzewo[v][i][i] = 0;
      drzewo[v][2][2] = 1;
      drzewo[v][2][3] = 0;
    }
    if (tab[a] == 4) {
      for (int i = 0; i <= 4; i++) drzewo[v][i][i] = 0;
      drzewo[v][3][3] = 1;
      drzewo[v][3][4] = 0;
    }
    if (tab[a] == -1) {
      for (int i = 0; i <= 4; i++) drzewo[v][i][i] = 0;
      drzewo[v][3][3] = 1;
      drzewo[v][4][4] = 1;
    }
    return;
  }
  start((v << 1), a, (a + b) >> 1);
  start((v << 1) ^ 1, (a + b + 2) >> 1, b);
  for (int i = 0; i <= 4; i++)
    for (int j = i; j <= 4; j++)
      for (int l = j; l <= 4; l++)
        drzewo[v][i][l] = min(drzewo[v][i][l], drzewo[(v << 1)][i][j] +
                                                   drzewo[(v << 1) ^ 1][j][l]);
}
void czyt(int v, int a, int b, int graa, int grab) {
  if (a >= graa && b <= grab) {
    for (int i = 0; i <= 4; i++) {
      now[i] = sta[i];
      sta[i] = inf;
    }
    for (int i = 0; i <= 4; i++)
      for (int j = i; j <= 4; j++)
        sta[j] = min(sta[j], now[i] + drzewo[v][i][j]);
    return;
  }
  if (a > grab || b < graa) {
    return;
  }
  czyt((v << 1), a, (a + b) >> 1, graa, grab);
  czyt((v << 1) ^ 1, (a + b + 2) >> 1, b, graa, grab);
}
int main() {
  scanf("%d%d", &n, &q);
  scanf("%s", wcz + 1);
  n1 = potenga(n);
  for (int i = 1; i <= n; i++) {
    if (wcz[i] == '2') tab[i] = 1;
    if (wcz[i] == '0') tab[i] = 2;
    if (wcz[i] == '1') tab[i] = 3;
    if (wcz[i] == '6') tab[i] = -1;
    if (wcz[i] == '7') tab[i] = 4;
  }
  start(1, 1, n1);
  while (q--) {
    int p1, p2;
    scanf("%d%d", &p1, &p2);
    sta[1] = sta[2] = sta[3] = sta[4] = inf;
    sta[0] = 0;
    czyt(1, 1, n1, p1, p2);
    if (sta[4] < inf)
      printf("%d\n", sta[4]);
    else
      printf("-1\n");
  }
  return 0;
}
