#include <bits/stdc++.h>
using namespace std;
template <class F> class y_combinator {
    F f;

   public:
    y_combinator(F&& f) : f(std::forward<F>(f)) {}
    template <class... Args> auto operator()(Args&&... args) const { return f(*this, std::forward<Args>(args)...); }
};
using ll = long long;
using ld = long double;
using u8 = uint8_t;
using u32 = uint32_t;
using u64 = uint64_t;
using vi = vector<int>;
using vl = vector<ll>;
using pii = pair<int, int>;
using pll = pair<ll, ll>;
template <class T, class U = std::less<T>> using prique = std::priority_queue<T, std::vector<T>, U>;
inline constexpr int popcnt(u64 x) noexcept { return __builtin_popcountll(x); }
template <class T> T floor(T a, T b) noexcept { return a / b - (a % b && (a ^ b) < 0); }
template <class T> T ceil(T a, T b) noexcept { return floor(a + b - 1, b); }
template <class T> bool chmin(T& x, const T& y) noexcept { return (x > y ? x = y, true : false); }
template <class T> bool chmax(T& x, const T& y) noexcept { return (x < y ? x = y, true : false); }
void SCAN() {}
template <class H, class... T> void SCAN(H& h, T&... t) { std::cin >> h, SCAN(t...); }
#define INT(...)     \
    int __VA_ARGS__; \
    SCAN(__VA_ARGS__)
#define LL(...)            \
    long long __VA_ARGS__; \
    SCAN(__VA_ARGS__)
#define LD(...)              \
    long double __VA_ARGS__; \
    SCAN(__VA_ARGS__)
#define STR(...)             \
    std::string __VA_ARGS__; \
    SCAN(__VA_ARGS__)
#define CHAR(...)     \
    char __VA_ARGS__; \
    SCAN(__VA_ARGS__)
#define VEC(type, name, size)     \
    std::vector<type> name(size); \
    for (int i = 0; i < (int)size; i++) SCAN(name[i]);
#define VV(type, name, h, w)                                      \
    std::vector<std::vector<type>> name(h, std::vector<type>(w)); \
    for (int i = 0; i < (int)h; i++)                              \
        for (int j = 0; j < (int)w; j++) SCAN(name[i][j]);
#define overload4(a, b, c, d, e, ...) e
#define rep1(a) for (long long _i = 0; _i < (a); _i++)
#define rep2(i, a) for (long long i = 0; i < (a); i++)
#define rep3(i, a, b) for (long long i = (a); i < (b); i++)
#define rep4(i, a, b, c) for (long long i = (a); i < (b); i += (c))
#define rep(...) overload4(__VA_ARGS__, rep4, rep3, rep2, rep1)(__VA_ARGS__)
#define rrep(i, a, b, c) for (long long i = (a); i > (b); i += (c))
#define all(x) std::begin(x), std::end(x)
#define rall(x) std::rbegin(x), std::rend(x)
#define len(x) (long long)(size(x))
#define pb push_back
#ifndef LOCAL
#define debug(...)
#endif

#include <atcoder/segtree>
int op(int a, int b) { return max(a, b); }
int e() { return -1; }
using STree = atcoder::segtree<int, op, e>;
void run_case() {
    INT(N, Q);
    STR(S);
    array<STree, 10> seg;
    vector<vector<int>> init(10, vector<int>(N, e()));
    rep(i, 10) {
        rep(j, N) {
            if (S[j] - '0' == i) init[i][j] = j;
        }
    }
    rep(i, 10) seg[i] = STree(init[i]);
    vector<int> ss;
    rep(x, 0, 1000, 8) if (x >= 100) ss.push_back(x);
    auto f = [&](int l, int r, int tar) -> int {
        vi ids;
        vector<pii> his;
        int ans = 0;
        {
            int x = tar;
            bool ok = true;
            while (x) {
                int d = x % 10;
                x /= 10;
                int t = seg[d].prod(l, r);
                if (t == -1) {
                    ok = false;
                    break;
                }
                his.push_back({d, t});
                assert(seg[d].get(t) == t);
                seg[d].set(t, -1);
                ids.push_back(t);
            }
            if (!ok) {
                for (auto [id, val] : his) seg[id].set(val, val);
                return 1e9;
            }
        }
        reverse(all(ids));
        debug(ids);
        rep(i, len(ids)) {
            ans += r - i - ids[i];
            rep(j, i + 1, len(ids)) if(ids[j] > ids[i]) ids[j]++;
        }
        for (auto [id, val] : his) seg[id].set(val, val);
        debug(ans, tar, l, r);
        return ans;
        return ans;
    };
    rep(Q) {
        INT(l, r);
        l--;
        int ans = 1e9;
        for (int tar : ss) {
            chmin(ans, f(l, r, tar));
        }
        cout << (ans == 1e9 ? -1 : ans) << "\n";
    }
}
int main() {
    std::ios_base::sync_with_stdio(false);
    std::cin.tie(nullptr);
    std::fixed(std::cout).precision(16);
    int T = 1;
    while (T--) run_case();
    return 0;
}