#include <bits/stdc++.h>
using namespace std;
#define ll long long
#define pii pair<int, int>
#define pll pair<ll, ll>
#define vi vector<int>
#define vl vector<ll>
#define ov4(a, b, c, d, name, ...) name
#define rep3(i, a, b, c) for(ll i = (a); i < (b); i += (c))
#define rep2(i, a, b) rep3(i, a, b, 1)
#define rep1(i, n) rep2(i, 0, n)
#define rep0(n) rep1(aaaaa, n)
#define rep(...) ov4(__VA_ARGS__, rep3, rep2, rep1, rep0)(__VA_ARGS__)
#define per(i, a, b) for(ll i = (a)-1; i >= (b); i--)
#define fore(e, v) for(auto&& e : v)
#define all(a) begin(a), end(a)
#define sz(a) (int)(size(a))
#define lb(v, x) (lower_bound(all(v), x) - begin(v))
#define eb emplace_back

template<typename T, typename S> bool chmin(T& a, const S& b) { return a > b ? a = b, 1 : 0; }
template<typename T, typename S> bool chmax(T& a, const S& b) { return a < b ? a = b, 1 : 0; }

const int INF = 1e9 + 100;
const ll INFL = 3e18 + 100;

#define i128 __int128_t

struct _ {
   _() { cin.tie(0)->sync_with_stdio(0), cout.tie(0); }
} __;

template<class S, S (*op)(S, S), S (*e)()> struct segtree {
   segtree(int n) : segtree(vector<S>(n, e())) {}
   segtree(const vector<S>& v) : n(sz(v)) {
      s = bit_ceil(unsigned(n));
      log = countr_zero(unsigned(s));
      d = vector<S>(2 * s, e());
      rep(i, n) d[s + i] = v[i];
      per(i, s, 1) update(i);
   }
   void set(int p, S x) {
      d[p += s] = x;
      rep(i, 1, log + 1) update(p >> i);
   }
   S prod(int l, int r) const {
      S sml = e(), smr = e();
      l += s, r += s;
      while(l < r) {
         if(l & 1) sml = op(sml, d[l++]);
         if(r & 1) smr = op(d[--r], smr);
         l >>= 1, r >>= 1;
      }
      return op(sml, smr);
   }
   S all_prod() const { return d[1]; }
   template<typename F> int max_right(int l, F f) const {
      if(l == n) return n;
      l += s;
      S sm = e();
      do {
         while(~l & 1) l >>= 1;
         if(!f(op(sm, d[l]))) {
            while(l < s) {
               l <<= 1;
               if(f(op(sm, d[l]))) sm = op(sm, d[l++]);
            }
            return l - s;
         }
         sm = op(sm, d[l++]);
      } while((l & -l) != l);
      return n;
   }
   template<typename F> int min_left(int r, F f) const {
      if(!r) return 0;
      r += s;
      S sm = e();
      do {
         r--;
         while(r > 1 and r & 1) r >>= 1;
         if(!f(op(d[r], sm))) {
            while(r < s) {
               r = (2 * r + 1);
               if(f(op(d[r], sm))) sm = op(d[r--], sm);
            }
            return r + 1 - s;
         }
         sm = op(d[r], sm);
      } while((r & -r) != r);
      return 0;
   }

   private:
   int n, s, log;
   vector<S> d;
   void update(int k) { d[k] = op(d[k * 2], d[k * 2 + 1]); }
};


const int M = 4;
struct S {
    vector<int> to, cnt;
};
// a ... fl
// e ... r?
// i ... mt
// o ... ds
const vector<string> LL = {"fl", "r?", "mt", "ds"};
const string RR = "aeio";

S e() {
    S z;
    z.cnt.resize(1<<M);
    z.to.resize(1<<M);
    rep(i, 1<<M)z.cnt[i] = 0, z.to[i] = i;
    return z;
}
S op(S x, S y) {
    S z = e();
    rep(i, 1 << M) {
        z.to[i] = y.to[x.to[i]];
        z.cnt[i] = x.cnt[i] + y.cnt[x.to[i]];
    }
    return z;
}


S get(char x) {
    S z = e();
    rep(i, 1 << M) {
        int to = i, cnt = 0;
        rep(j, M) {
            if (LL[j][0] == x || LL[j][1] == x) to |= (1 << j);
            if (i >> j & 1 && RR[j] == x) {
                to = 0;
                cnt = 1;
                break;
            }
        }
        z.to[i] = to;
        z.cnt[i] = cnt;
        
    }
    return z;
}

void solve() {
    int n, q;cin >> n >> q;
    string s;cin >> s;
    vector<S> a(n);
    rep(i, n) a[i] = get(s[i]);

    segtree<S, op, e> st(a);

    rep(q) {
        string t;cin >> t;
        if (t == "?") {
            int l, r;cin >> l >> r;
            l--;
            cout << r - l - 2 * st.prod(l, r).cnt[0] << endl;
        }
        else {
            int l, r;cin >> l >> r;
            l--;
            string news;cin >> news;

            rep(i, l, r) {
                st.set(i, get(news[i-l]));
            }
        }
    }
}   

int main() {
    // int T;cin >> T;
    int T = 1;
    while (T--) {
        solve();
    }
}