#include <bits/stdc++.h>
using namespace std;
using ll = long long;
const ll INF = LLONG_MAX / 4;
#define rep(i, a, b) for(ll i = a; i < b; i++)
#define all(a) begin(a), end(a)
ll sz(auto& a) { return size(a); }
template<class T> bool chmin(T& a, T b) { if(a <= b) return 0; a = b; return 1; }
template<class T> bool chmax(T& a, T b) { if(a >= b) return 0; a = b; return 1; }

struct M {
    uint64_t x;
    operator uint64_t() const { return x; }
    operator uint64_t&() { return x; }
    uint64_t col(ll j) const {
        return x >> j & 0x0101010101;
    }
    uint8_t row(ll i) const {
        return x >> (i * 8) & 0xFF;
    }
};
M match(M a, M b) {
    M c = {0};
    rep(j, 0, 7) {
        const ll i = vector{0, 1, 2, 3, 0, 3, 2}[j];
        c |= a.col(j) * b.row(i);
    }
    return c;
}
M mismatch(M a, ll pa, M b, ll pb) {
    uint64_t c = 0, r = 0;
    rep(i, 0, 5) r |= b.row(i);
    if(pb == 0) rep(i, 0, 5) r |= a.row(i);
    rep(j, 0, 8) c |= a.col(j);
    if(pa == 0) rep(j, 0, 8) c |= b.col(j);
    return {c * r};
}
struct T {
    ll p;
    M bit0, bit1;
};
const T e = {0, 1ULL << 39, 1ULL << 39};
T one(char c) {
    T a = e;
    rep(i, 0, 4) if(c == "oeia"[i]) {
        a.bit0 |= 1ULL << (i * 8 + 7);
        a.bit1 = a.bit0;
        return a;
    }
    rep(i, 0, 7) if(c == "drmfslt"[i]) {
        a.bit0 |= 1ULL << (32 + i);
        a.bit1 = a.bit0;
        return a;
    }
    return a;
}
T op(T a, T b) {
    T c;
    auto& [p, bit0, bit1] = c;
    p = a.p + b.p + 1;
    bit0 = match(a.bit0, b.bit0);
    bit1 = mismatch(a.bit0, a.p, b.bit0, b.p);
    bit1 |= match(a.bit0, b.bit1);
    bit1 |= match(a.bit1, b.bit0);
    if(bit0.x) {
        return c;
    }
    p--;
    bit0 = bit1;
    bit1 = match(a.bit1, b.bit1);
    bit1 |= mismatch(a.bit0, a.p, b.bit1, b.p - 1);
    bit1 |= mismatch(a.bit1, a.p - 1, b.bit0, b.p);
    return c;
}

int main() {
    cin.tie(0)->sync_with_stdio(0);
    ll N, Q;
    cin >> N >> Q;
    string S;
    cin >> S;
    vector<T> seg(N * 2);
    auto set = [&](ll i, char c) {
        i += N;
        seg[i] = one(c);
        while(i >>= 1) seg[i] = op(seg[i * 2], seg[i * 2 + 1]);
    };
    rep(i, 0, N) set(i, S[i]);
    while(Q--) {
        char c;
        cin >> c;
        ll L, R;
        cin >> L >> R;
        L--;
        const ll w = R - L;
        if(c == '?') {
            L += N;
            R += N;
            T pL = e, pR = e;
            for(; L < R; L >>= 1, R >>= 1) {
                if(L & 1) pL = op(pL, seg[L++]);
                if(R & 1) pR = op(seg[--R], pR);
            }
            T ans = op(pL, pR);
            cout << w - ans.p * 2 << '\n';
        }
        else {
            string S;
            cin >> S;
            rep(i, 0, w) set(L + i, S[i]);
        }
    }
}