#include <bits/stdc++.h>

using i64 = long long;

constexpr int inf = 1E9;

struct Info {
    int f[5];
    int g[5];

    Info() : f{}, g{0, 2, 4, 8, 16} {}
};

Info operator+(Info a, Info b) {
    Info c;
    for (int i = 0; i <= 4; i++) {
        if (a.g[i] == 0) {
            c.f[i] = a.f[i] + b.f[i];
            c.g[i] = b.g[i];
        } else {
            for (int j = 1; j <= 4; j++) {
                if (a.g[i] >> j & 1) {
                    int v = a.f[i] + b.f[j];
                    int s = b.g[j];
                    if (v > c.f[i]) {
                        c.f[i] = v;
                        c.g[i] = s;
                    } else if (v == c.f[i]) {
                        c.g[i] |= s;
                    }
                }
            }
        }
    }
    return c;
}

constexpr int N = 1 << 20;

Info t[N];

Info val[N];

void build(int p, int l, int r) {
    if (r - l == 1) {
        t[p] = val[l];
        return;
    }
    int m = (l + r) / 2;
    build(2 * p, l, m);
    build(2 * p + 1, m, r);
    t[p] = t[2 * p] + t[2 * p + 1];
}

void modify(int p, int l, int r, int x, const Info &v) {
    if (r - l == 1) {
        t[p] = v;
        return;
    }
    int m = (l + r) / 2;
    if (x < m) {
        modify(2 * p, l, m, x, v);
    } else {
        modify(2 * p + 1, m, r, x, v);
    }
    t[p] = t[2 * p] + t[2 * p + 1];
}

Info query(int p, int l, int r, int x, int y) {
    if (l >= y || r <= x) {
        return {};
    }
    if (l >= x && r <= y) {
        return t[p];
    }
    int m = (l + r) / 2;
    return query(2 * p, l, m, x, y) + query(2 * p + 1, m, r, x, y);
}

Info ch[128];

int id[128] {};

int main() {
    std::ios::sync_with_stdio(false);
    std::cin.tie(nullptr);

    id['a'] = 1;
    id['e'] = 2;
    id['i'] = 3;
    id['o'] = 4;

    for (auto s : std::vector<std::string>{"do", "re", "mi", "fa", "so", "la", "ti"}) {
        for (int i = 0; i <= 4; i++) {
            ch[s[0]].g[i] = (i == 0 ? 0 : 1 << i) | 1 << id[s[1]];
        }
        ch[s[1]].f[id[s[1]]] = 1;
        ch[s[1]].g[id[s[1]]] = 0;
    }

    int n, q;
    std::cin >> n >> q;

    std::string s;
    std::cin >> s;

    for (int i = 0; i < n; i++) {
        val[i] = ch[s[i]];
    }
    build(1, 0, n);

    while (q--) {
        char c;
        std::cin >> c;

        if (c == '?') {
            int l, r;
            std::cin >> l >> r;
            l--;

            auto res = query(1, 0, n, l, r);
            int ans = r - l - 2 * res.f[0];
            std::cout << ans << "\n";
        } else {
            int l, r;
            std::cin >> l >> r;
            l--;
            std::string t;
            std::cin >> t;

            for (int i = l; i < r; i++) {
                modify(1, 0, n, i, ch[t[i - l]]);
            }
        }
    }

    return 0;
}