#include<bits/stdc++.h>

#define LL long long

#define LD long double

#define ull unsigned long long

#define fi first

#define se second

#define mk make_pair

#define PLL pair<LL, LL>

#define PLI pair<LL, int>

#define PII pair<int, int>

#define SZ(x) ((int)x.size())

#define ALL(x) (x).begin(), (x).end()

#define fio ios::sync_with_stdio(false); cin.tie(0);

using namespace std;

const int N = 2e5 + ;

const int inf = 0x3f3f3f3f;

const LL INF = 0x3f3f3f3f3f3f3f3f;

const int mod = 1e9 + ;

const double eps = 1e-;

const double PI = acos(-);

template<class T, class S> inline void add(T& a, S b) {a += b; if(a >= mod) a -= mod;}

template<class T, class S> inline void sub(T& a, S b) {a -= b; if(a < ) a += mod;}

template<class T, class S> inline bool chkmax(T& a, S b) {return a < b ? a = b, true : false;}

template<class T, class S> inline bool chkmin(T& a, S b) {return a > b ? a = b, true : false;}

#define lson l, mid, rt << 1

#define rson mid + 1, r, rt << 1 | 1

struct info {

    int a[][];

    info() {

        memset(a, inf, sizeof(a));

    }

    void go(char c) {

        for(int i = ; i < ; i++)

            for(int j = ; j < ; j++)

                a[i][j] = i == j ?  : inf;

        if(c == '') a[][] = , a[][] = ;

        else if(c == '') a[][] = , a[][] = ;

        else if(c == '') a[][] = , a[][] = ;

        else if(c == '') a[][] = , a[][] = ;

        else if(c == '') a[][] = , a[][] = ;

    }

};

info operator + (const info& x, const info& y) {

    info z;

    for(int i = ; i < ; i++)

        for(int j = i; j < ; j++)

            for(int k = i; k < ; k++)

                chkmin(z.a[i][j], x.a[i][k] + y.a[k][j]);

    return z;

}

info a[N << ];

void build(char* s, int l, int r, int rt) {

    if(l == r) {

        a[rt].go(s[l]);

        return;

    }

    int mid = l + r >> ;

    build(s, lson); build(s, rson);

    a[rt] = a[rt << ] + a[rt <<  | ];

}

info query(int L, int R, int l, int r, int rt) {

    if(L <= l && r <= R) return a[rt];

    int mid = l + r >> ;

    if(R <= mid) return query(L, R, lson);

    else if(L > mid) return query(L, R, rson);

    else return query(L, R, lson) + query(L, R, rson);

}

int n, q;

char s[N];

int main() {

    scanf("%d%d", &n, &q);

    scanf("%s", s + );

    build(s, , n, );

    while(q--) {

        int L, R;

        scanf("%d%d", &L, &R);

        info ans = query(L, R, , n, );

        printf("%d\n", ans.a[][] == inf ? - : ans.a[][]);

    }

    return ;

}

/*

*/