Problem:
Score : 300 points

Problem Statement

You are given a string S of length N consisting of A, C, G and T. Answer the following Q queries:

Query i (1 \leq i \leq Q): You will be given integers l_i and r_i (1 \leq l_i < r_i \leq N). Consider the substring of S starting at index l_i and ending at index r_i (both inclusive). In this string, how many times does AC occurs as a substring?

Notes

A substring of a string T is a string obtained by removing zero or more characters from the beginning and the end of T.

For example, the substrings of ATCODER include TCO, AT, CODER, ATCODER and (the empty string), but not AC.

Constraints

2 \leq N \leq 10^5

1 \leq Q \leq 10^5

S is a string of length N.

Each character in S is A, C, G or T.

1 \leq l_i < r_i \leq N

Input

Input is given from Standard Input in the following format:

N Q
S
l_1 r_1
:
l_Q r_Q

Output

Print Q lines. The i-th line should contain the answer to the i-th query.

Sample Input 1

8 3
ACACTACG
3 7
2 3
1 8

Sample Output 1

2
0
3

Query 1: the substring of S starting at index 3 and ending at index 7 is ACTAC. In this string, AC occurs twice as a substring.

Query 2: the substring of S starting at index 2 and ending at index 3 is CA. In this string, AC occurs zero times as a substring.

Query 3: the substring of S starting at index 1 and ending at index 8 is ACACTACG. In this string, AC occurs three times as a substring.

Solution in C++14 (GCC 5.4.1) (judge verdict: Accepted)

#include <bits/stdc++.h>
using namespace std;

// Define
using ll = long long;
using ull = unsigned long long;
using ld = long double;
const ll dx[4] = {1, 0, -1, 0};
const ll dy[4] = {0, 1, 0, -1};
const ll MOD = 1e9 + 7;
const ll mod = 998244353;
const ll inf = 1 << 30;
const ll LINF = LONG_MAX;
const ll INF = 1LL << 60;
const ull MAX = ULONG_MAX;
#define mp make_pair
#define pb push_back
#define elif else if
#define endl '\n'
#define space ' '
#define def inline auto
#define func inline constexpr ll
#define run(a) __attribute__((constructor)) def _##a()
#define all(v) begin(v), end(v)
#define rall(v) rbegin(v), rend(v)
#define input(a) scanf("%lld", &(a))
#define print(a) printf("%lld\n", (a))
#define fi first
#define se second
#define ok(a, b) (0 <= (a) && (a) < (b))
template <class T> using vvector = vector<vector<T>>;
template <class T> using pvector = vector<pair<T, T>>;
template <class T>
using rpriority_queue = priority_queue<T, vector<T>, greater<T>>;

template <class T> bool chmax(T &a, const T &b) {
    if (a < b) {
        a = b;
        return 1;
    }
    return 0;
}
template <class T> bool chmin(T &a, const T &b) {
    if (a > b) {
        a = b;
        return 1;
    }
    return 0;
}

// Debug
#define debug(...)                                                             \
    {                                                                          \
        cerr << __LINE__ << ": " << #__VA_ARGS__ << " = ";                     \
        for (auto &&X : {__VA_ARGS__}) cerr << "[" << X << "] ";               \
        cerr << endl;                                                          \
    }

#define dump(a, h, w)                                                          \
    {                                                                          \
        cerr << __LINE__ << ": " << #a << " = [" << endl;                      \
        rep(__i, h) {                                                          \
            rep(__j, w) { cerr << a[__i][__j] << space; }                      \
            cerr << endl;                                                      \
        }                                                                      \
        cerr << "]" << endl;                                                   \
    }

#define vdump(a, n)                                                            \
    {                                                                          \
        cerr << __LINE__ << ": " << #a << " = [";                              \
        rep(__i, n) if (__i) cerr << space << a[__i];                          \
        else cerr << a[__i];                                                   \
        cerr << "]" << endl;                                                   \
    }

// Loop
#define inc(i, a, n) for (ll i = (a), _##i = (n); i <= _##i; ++i)
#define dec(i, a, n) for (ll i = (a), _##i = (n); i >= _##i; --i)
#define rep(i, n) for (ll i = 0, _##i = (n); i < _##i; ++i)
#define each(i, a) for (auto &&i : a)
#define loop() for (;;)

// Stream
#define fout(n) cout << fixed << setprecision(n)
#define fasten cin.tie(0), ios::sync_with_stdio(0)
run(0) { fasten, fout(10); }

// Speed
#pragma GCC optimize("O3")
#pragma GCC target("avx")

// Math
func gcd(ll a, ll b) { return b ? gcd(b, a % b) : a; }
func lcm(ll a, ll b) { return a * b / gcd(a, b); }
func sign(ll a) { return a ? abs(a) / a : 0; }

inline constexpr ll modulo(const ll n, const ll m = MOD) {
    ll k = n % m;
    return k + m * (k < 0);
}

inline constexpr ll chmod(ll &n, const ll m = MOD) {
    n %= m;
    return n += m * (n < 0);
}

inline constexpr ll mpow(ll a, ll n, const ll m = MOD) {
    ll r = 1;
    while (n) {
        if (n & 1) r *= a;
        chmod(r, m);
        a *= a;
        chmod(a, m);
        n >>= 1;
    }
    return r;
}

inline ll inv(const ll n, const ll m = MOD) {
    ll a = n, b = m, x = 1, y = 0;
    while (b) {
        ll t = a / b;
        a -= t * b;
        swap(a, b);
        x -= t * y;
        swap(x, y);
    }
    return modulo(x, m);
}

struct Factor {
    inline vector<ll> factors(ll N) {
        vector<ll> A;
        ll i = 2;
        while (i * i <= N) {
            if (N % i == 0) {
                A.push_back(i);
                N /= i;
            } else {
                i++;
            }
        }
        if (N != 1) A.push_back(N);
        sort(all(A));
        return A;
    }
    inline vector<ll> divisor(ll N) {
        vector<ll> A;
        inc(i, 1, sqrt(N)) {
            if (N % i == 0) {
                A.push_back(i);
                if (i * i != N) A.push_back(N / i);
            }
        }
        sort(all(A));
        return A;
    }
};

struct csum {
    ll N;
    vector<ll> A, S;
    csum(vector<ll> v) : A(v), S(1) { each(k, v) S.push_back(k + S.back()); }
    ll sum(ll l, ll r) { return S[r] - S[l]; }
    ll lsum(ll r) { return S[r]; }
    ll rsum(ll l) { return S.back() - S[l]; }
};

template <ull mod = MOD> struct mi {
    inline constexpr ll modulo(const ll n, const ll m) const noexcept {
        ll k = n % m;
        return k + m * (k < 0);
    }

    ll num;
    inline constexpr mi() noexcept : num() { num = 0; }
    inline constexpr mi(const int n) noexcept : num() { num = modulo(n, mod); }
    inline constexpr mi(const ll n) noexcept : num() { num = modulo(n, mod); }

    inline constexpr mi<mod> inv() const noexcept {
        ll a = num, b = mod, x = 1, y = 0;
        while (b) {
            ll t = a / b;
            a -= t * b;
            swap(a, b);
            x -= t * y;
            swap(x, y);
        }
        return mi<mod>(x);
    }
    inline constexpr mi<mod> inv(ll n) const noexcept {
        ll a = n, b = mod, x = 1, y = 0;
        while (b) {
            ll t = a / b;
            a -= t * b;
            swap(a, b);
            x -= t * y;
            swap(x, y);
        }
        return mi<mod>(x);
    }
    inline constexpr mi<mod> inv(const mi<mod> m) const noexcept {
        return inv(m.num);
    }

    inline constexpr mi<mod> operator+() const noexcept { return mi(num); }
    inline constexpr mi<mod> operator+(const int n) const noexcept {
        return mi<mod>(num + n);
    }
    inline constexpr mi<mod> operator+(const ll n) const noexcept {
        return mi<mod>(num + n);
    }
    inline constexpr mi<mod> operator+(const mi<mod> m) const noexcept {
        return mi<mod>(num + m.num);
    }
    inline constexpr mi<mod> operator-() const noexcept { return -num; }
    inline constexpr mi<mod> operator-(const int n) const noexcept {
        return mi<mod>(num - n);
    }
    inline constexpr mi<mod> operator-(const ll n) const noexcept {
        return mi<mod>(num - n);
    }
    inline constexpr mi<mod> operator-(const mi<mod> m) const noexcept {
        return mi<mod>(num - m.num);
    }
    inline constexpr mi<mod> operator*(const int n) const noexcept {
        return mi<mod>(num * n);
    }
    inline constexpr mi<mod> operator*(const ll n) const noexcept {
        return mi<mod>(num * n);
    }
    inline constexpr mi<mod> operator*(const mi<mod> m) const noexcept {
        return mi<mod>(num * m);
    }
    inline constexpr mi<mod> operator/(const int n) const noexcept {
        return mi<mod>(num * (ll) inv(n));
    }
    inline constexpr mi<mod> operator/(const ll n) const noexcept {
        return mi<mod>(num * (ll) inv(n));
    }
    inline constexpr mi<mod> operator/(const mi<mod> m) const noexcept {
        return mi<mod>(num * (ll) inv(m));
    }
    inline constexpr mi<mod> &operator=(const int n) noexcept {
        num = modulo(n, mod);
        return *this;
    }
    inline constexpr mi<mod> &operator=(const ll n) noexcept {
        num = modulo(n, mod);
        return *this;
    }
    inline constexpr mi<mod> &operator=(const mi<mod> m) noexcept {
        num = m.num;
        return *this;
    }
    inline constexpr mi<mod> &operator+=(const int n) noexcept {
        num = modulo(num + n, mod);
        return *this;
    }
    inline constexpr mi<mod> &operator+=(const ll n) noexcept {
        num = modulo(num + n, mod);
        return *this;
    }
    inline constexpr mi<mod> &operator+=(const mi<mod> m) noexcept {
        num = modulo(num + m.num, mod);
        return *this;
    }
    inline constexpr mi<mod> &operator++() noexcept {
        num = modulo(num + 1, mod);
        return *this;
    }
    inline constexpr mi<mod> operator++(int) noexcept {
        mi &pre = *this;
        num = modulo(num + 1, mod);
        return pre;
    }
    inline constexpr mi<mod> &operator-=(const int n) noexcept {
        num = modulo(num - n, mod);
        return *this;
    }
    inline constexpr mi<mod> &operator-=(const ll n) noexcept {
        num = modulo(num - n, mod);
        return *this;
    }
    inline constexpr mi<mod> &operator-=(const mi<mod> m) noexcept {
        num = modulo(num - m.num, mod);
        return *this;
    }
    inline constexpr mi<mod> &operator--() noexcept {
        num = modulo(num - 1, mod);
        return *this;
    }
    inline constexpr mi<mod> operator--(int) noexcept {
        mi &pre = *this;
        num = modulo(num - 1, mod);
        return pre;
    }
    inline constexpr mi<mod> &operator*=(const int n) noexcept {
        num = modulo(num * n, mod);
        return *this;
    }
    inline constexpr mi<mod> &operator*=(const ll n) noexcept {
        num = modulo(num * n, mod);
        return *this;
    }
    inline constexpr mi<mod> &operator*=(const mi<mod> m) noexcept {
        num = modulo(num * m.num, mod);
        return *this;
    }
    inline constexpr mi<mod> &operator/=(const int n) noexcept {
        num = modulo(num * (ll) inv(n), mod);
        return *this;
    }
    inline constexpr mi<mod> &operator/=(const ll n) noexcept {
        num = modulo(num * (ll) inv(n), mod);
        return *this;
    }
    inline constexpr mi<mod> &operator/=(const mi<mod> m) noexcept {
        num = modulo(num * (ll) inv(m), mod);
        return *this;
    }
    inline constexpr mi<mod> operator==(const int n) const noexcept {
        return num == modulo(n, mod);
    }
    inline constexpr mi<mod> operator==(const ll n) const noexcept {
        return num == modulo(n, mod);
    }
    inline constexpr mi<mod> operator==(const mi<mod> m) const noexcept {
        return num == m.num;
    }
    inline constexpr mi<mod> operator!=(const int n) const noexcept {
        return num != modulo(n, mod);
    }
    inline constexpr mi<mod> operator!=(const ll n) const noexcept {
        return num != modulo(n, mod);
    }
    inline constexpr mi<mod> operator!=(const mi<mod> m) const noexcept {
        return num != m.num;
    }
    constexpr operator int() const noexcept { return num; }
    constexpr operator ll() const noexcept { return num; }
    friend std::istream &operator>>(std::istream &, const mi<> &);
    friend std::ostream &operator<<(std::ostream &, const mi<> &);
};

template <ull mod = MOD>
inline constexpr mi<mod> operator+(const int n, const mi<mod> m) noexcept {
    return mi<mod>(n + m.num);
}
template <ull mod = MOD>
inline constexpr mi<mod> operator+(const ll n, const mi<mod> m) noexcept {
    return mi<mod>(n + m.num);
}
template <ull mod = MOD>
inline constexpr mi<mod> operator-(const int n, const mi<mod> m) noexcept {
    return mi<mod>(n - m.num);
}
template <ull mod = MOD>
inline constexpr mi<mod> operator-(const ll n, const mi<mod> m) noexcept {
    return mi<mod>(n - m.num);
}
template <ull mod = MOD>
inline constexpr mi<mod> operator*(const int n, const mi<mod> m) noexcept {
    return mi<mod>(n * m.num);
}
template <ull mod = MOD>
inline constexpr mi<mod> operator*(const ll n, const mi<mod> m) noexcept {
    return mi<mod>(n * m.num);
}
template <ull mod = MOD>
inline constexpr mi<mod> operator/(const int n, const mi<mod> m) noexcept {
    return mi<mod>(n * (ll) m.inv());
}
template <ull mod = MOD>
inline constexpr mi<mod> operator/(const ll n, const mi<mod> m) noexcept {
    return mi<mod>(n * (ll) m.inv());
}
inline constexpr mi<MOD> operator""_m(ull n) { return mi<MOD>((ll) n); }

template <ull mod = MOD>
inline constexpr mi<mod> pow(mi<mod> m, ll n) noexcept {
    mi<mod> r = mi<mod>(1);
    while (n) {
        if (n & 1) r *= m;
        m *= m;
        n >>= 1;
    }
    return r;
}
template <ull mod> istream &operator>>(istream &is, mi<mod> &m) {
    is >> m.num;
    return is;
}
template <ull mod> ostream &operator<<(ostream &is, mi<mod> &m) {
    is << (ll) m;
    return is;
}

template <ull mod = MOD> struct modmath {
    ll max;
    vector<mi<mod>> fac, inv;
    modmath() : max(1 << 20), fac(max + 1), inv(max + 1) {
        fac[0] = mi<mod>(1);
        rep(i, max) fac[i + 1] = fac[i] * (i + 1);
        inv[max] = fac[max].inv();
        dec(i, max - 1, 0) inv[i] = inv[i + 1] * (i + 1);
    }
    modmath(ll n) : max(n), fac(n + 1), inv(n + 1) {
        fac[0] = 1;
        rep(i, n) fac[i + 1] = fac[i] * (i + 1);
        inv[n] = 1 / fac[n];
        dec(i, n - 1, 0) inv[i] = inv[i + 1] * (i + 1);
    }

    inline mi<mod> fact(ll n) {
        if (n < 0) return mi<mod>(0);
        return fac[n];
    }
    inline mi<mod> perm(ll n, ll r) {
        if (r < 0 || n < r) return mi<mod>(0);
        return fac[n] * inv[n - r];
    }
    inline mi<mod> comb(ll n, ll r) {
        if (r < 0 || n < r) return mi<mod>(0);
        return fac[n] * inv[r] * inv[n - r];
    }
    inline mi<mod> nHr(ll n, ll r) { return comb(n + r - 1, n - 1); }
};

struct UFR {
    vector<ll> data;
    UFR(ll N) : data(N) { rep(i, N) data[i] = -1; }
    def root(ll x) {
        if (data[x] < 0)
            return x;
        else
            return data[x] = root(data[x]);
    }
    def unite(ll x, ll y) {
        ll root_x = root(x), root_y = root(y);
        if (root_x != root_y) {
            if (data[root_x] > data[root_y]) swap(root_x, root_y);
            data[root_x] -= data[root_x] == data[root_y];
            data[root_y] = root_x;
            return true;
        }
        return false;
    }
    def same(ll x, ll y) { return root(x) == root(y); }
};

struct position {
    ll x, y;
    position() {}
    position(ll a, ll b) : x(a), y(b) {}
    position next(ll i) { return {x + dx[i], y + dy[i]}; }
    ll mdist() { return abs(x) + abs(y); }
    double dist() { return sqrt(x * x + y * y); }
    double norm(ll d) {
        if (d == inf) return max(x, y);
        if (d == 1) return mdist();
        if (d == 2) return dist();
        return 0;
    }
    ll num(ll width) { return abs(x) * width + abs(y); }

    bool operator==(position a) { return x == a.x && y == a.y; }
    bool operator!=(position a) { return x != a.x || y != a.y; }
    bool operator<(position a) { return x < a.x && y < a.y; }
    bool operator>(position a) { return x > a.x && y > a.y; }
    bool operator<=(position a) { return x <= a.x && y <= a.y; }
    bool operator>=(position a) { return x >= a.x && y >= a.y; }
    position operator+(position a) { return position(x + a.x, y + a.y); }
    position operator-(position a) { return position(x - a.x, y - a.y); }
    position operator*(position a) { return position(x * a.x, y * a.y); }
    position operator/(position a) { return position(x / a.x, y / a.y); }
    position operator%(position a) { return position(x % a.x, y % a.y); }
    position complex(position a) {
        return position(x * a.x - y * a.y, x * a.y + y * a.x);
    }
    /*
        // for sort:
        bool operator<(position a) { return x ^ a.x ? x < a.x : y < a.y; }
        bool operator>(position a) { return x ^ a.x ? x > a.x : y > a.y; }
        bool operator<=(position a) { return x ^ a.x ? x < a.x : y <= a.y; }
        bool operator>=(position a) { return x ^ a.x ? x > a.x : y >= a.y; }
    */
};
position Origin = position(0, 0);
using pos = position;
using vec = position;

template <class T> struct Array {
    struct node {
        ll childl, childr;
        T data;
        node(ll l, ll r, T t) : childl(l), childr(r), data(t) {}
    };
    ll n, depth;
    vector<ll> versions;
    vector<ll> prev_versions;
    vector<node> nodes;
    Array(ll n = 1 << 20, T val = T()) : n(n), depth(0) {
        while (n /= 2) depth++;
        init(val);
    }
    void init(T val) {
        versions.push_back(0);
        prev_versions.push_back(0);
        rep(i, 2 * n - 1) {
            if (i < n - 1) {
                nodes.push_back(node(2 * i + 1, 2 * i + 2, T()));
            } else {
                nodes.push_back(node(0, 0, val));
            }
        }
    }
    void set(ll index, ll val, ll version = -1) {
        ll id, par = nodes.size(), left = 0, right = n;
        if (version == -1) {
            id = versions.back();
            version = versions.size() - 1;
        } else {
            id = versions[version];
        }
        versions.push_back(par);
        prev_versions.push_back(version);
        if (right == -1) right = n;
        rep(i, depth) {
            ll mid = (left + right) / 2;
            if (index < mid) {
                nodes.push_back(node(par + i + 1, nodes[id].childr, T()));
                id = nodes[id].childl;
                right = mid;
            } else {
                nodes.push_back(node(nodes[id].childl, par + i + 1, T()));
                id = nodes[id].childr;
                left = mid;
            }
        }
        nodes.push_back(node(0, 0, val));
    }
    T get(ll index, ll version = -1) {
        ll id, left = 0, right = n;
        if (version == -1) {
            id = versions.back();
        } else {
            id = versions[version];
        }
        rep(i, depth) {
            ll mid = (left + right) / 2;
            if (index < mid) {
                id = nodes[id].childl;
                right = mid;
            } else {
                id = nodes[id].childr;
                left = mid;
            }
        }
        return nodes[id].data;
    }
    ll latest() { return versions.size() - 1; }
};

struct BipartiteGraph {
    ll V;
    vector<vector<ll>> G;
    vector<ll> match;
    vector<bool> used;
    BipartiteGraph(ll N) : V(N), G(N), match(N), used(N) {}
    void addEdge(ll i, ll j) {
        G[i].push_back(j);
        G[j].push_back(i);
    }
    bool dfs(ll now) {
        used[now] = true;
        rep(i, G[now].size()) {
            ll next = G[now][i], w = match[next];
            if (w == -1 || (!used[w] && dfs(w))) {
                match[now] = next, match[next] = now;
                return true;
            }
        }
        return false;
    }
    ll matching() {
        ll res = 0;
        fill(all(match), -1);
        rep(i, V) {
            if (match[i] == -1) {
                fill(all(used), false);
                if (dfs(i)) res++;
            }
        }
        return res;
    }
};

signed main() {
    ll N, Q;
    cin >> N >> Q;
    string S;
    cin >> S;
    ll A[N];
    A[0] = 0;
    rep(i, N - 1) A[i + 1] = A[i] + (S[i] == 'A' && S[i + 1] == 'C');
    vdump(A, N);
    rep(i, Q) {
        ll l, r;
        cin >> l >> r;
        cout << A[r - 1] - A[l - 1] << endl;
    }
}