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#include <bits/stdc++.h>
using namespace std;
int N, M;
char sir[200009];
int ord[] = {2, 0, 1, 7};
struct state {
  int v[5][5];
} aint[800009], ansQ;
state operator+(state a, state b) {
  state c;
  for (int i = 0; i < 5; i++)
    for (int j = i; j < 5; j++) {
      c.v[i][j] = N + 3;
      for (int k = i; k <= j; k++)
        if (a.v[i][k] + b.v[k][j] < c.v[i][j])
          c.v[i][j] = a.v[i][k] + b.v[k][j];
    }
  return c;
}
void Build(int nod, int st, int dr) {
  if (st == dr) {
    int val = sir[st] - '0';
    for (int i = 0; i < 5; i++)
      for (int j = i; j < 5; j++) aint[nod].v[i][j] = N + 3;
    for (int i = 0; i < 5; i++) {
      if (i < 4 && val == ord[i]) {
        aint[nod].v[i][i] = 1;
        aint[nod].v[i][i + 1] = 0;
      } else
        aint[nod].v[i][i] = (i >= 3 && val == 6);
    }
    return;
  }
  int mij = (st + dr) >> 1;
  Build(nod << 1, st, mij);
  Build(nod << 1 | 1, mij + 1, dr);
  aint[nod] = aint[nod << 1] + aint[nod << 1 | 1];
}
void Query(int nod, int st, int dr, int x, int y) {
  if (x <= st && dr <= y) {
    if (x == st)
      ansQ = aint[nod];
    else
      ansQ = ansQ + aint[nod];
    return;
  }
  int mij = (st + dr) >> 1;
  if (x <= mij) Query(nod << 1, st, mij, x, y);
  if (mij < y) Query(nod << 1 | 1, mij + 1, dr, x, y);
}
int main() {
  scanf("%d %d\n", &N, &M);
  gets(sir + 1);
  Build(1, 1, N);
  while (M--) {
    int x, y;
    scanf("%d %d", &x, &y), Query(1, 1, N, x, y);
    if (ansQ.v[0][4] > N)
      printf("-1\n");
    else
      printf("%d\n", ansQ.v[0][4]);
  }
  return 0;
}
