#include<bits/stdc++.h>
#define LL long long
#define fi first
#define se second
#define mk make_pair
#define PLL pair<LL, LL>
#define PLI pair<LL, int>
#define PII pair<int, int>
#define SZ(x) ((int)x.size())
#define ull unsigned long long
using namespace std;const int N = 1e6 + 7;
const int inf = 0x3f3f3f3f;
const LL INF = 0x3f3f3f3f3f3f3f3f;
const int mod = 1e9 + 7;
const double eps = 1e-8;#define lson l, mid, rt << 1
#define rson mid + 1, r, rt << 1 | 1struct info {int up[2][2];int dn[2][2];
} a[N << 2];info operator + (const info& a, const info& b) {info ans;ans.up[0][0] = a.up[0][0] + b.up[0][0];ans.up[0][1] = max(a.up[0][0] + max(b.up[1][1], b.up[0][1]), a.up[0][1] + b.up[1][1]);ans.up[1][1] = a.up[1][1] + b.up[1][1];ans.dn[1][1] = a.dn[1][1] + b.dn[1][1];ans.dn[1][0] = max(a.dn[1][1] + max(b.dn[0][0], b.dn[1][0]), a.dn[1][0] + b.dn[0][0]);ans.dn[0][0] = a.dn[0][0] + b.dn[0][0];return ans;
}int lazy[N << 2];void change(int rt) {swap(a[rt].up[0][0], a[rt].dn[1][1]);swap(a[rt].up[1][1], a[rt].dn[0][0]);swap(a[rt].up[0][1], a[rt].dn[1][0]);
}void push(int rt) {if(lazy[rt]) {change(rt << 1); change(rt << 1 | 1);lazy[rt << 1] ^= 1;lazy[rt << 1 | 1] ^= 1;lazy[rt] = 0;}
}void build(int l, int r, int rt) {if(l == r) {int x; scanf("%1d", &x);if(x == 4) {a[rt].up[0][0] = 1;a[rt].up[0][1] = 0;a[rt].up[1][1] = 0;a[rt].dn[0][0] = 1;a[rt].dn[1][0] = 0;a[rt].dn[1][1] = 0;}else {a[rt].up[0][0] = 0;a[rt].up[0][1] = 0;a[rt].up[1][1] = 1;a[rt].dn[0][0] = 0;a[rt].dn[1][0] = 0;a[rt].dn[1][1] = 1;}return;}int mid = l + r >> 1;build(lson); build(rson);a[rt] = a[rt << 1] + a[rt << 1 | 1];
}void update(int L, int R, int l, int r, int rt) {if(l >= L && r <= R) {lazy[rt] ^= 1;change(rt);return;}int mid = l + r >> 1;push(rt);if(L <= mid) update(L, R, lson);if(R > mid)  update(L, R, rson);a[rt] = a[rt << 1] + a[rt << 1 | 1];
}int n, m;
char s[10];int main() {scanf("%d%d", &n, &m);build(1, n, 1);while(m--) {scanf("%s", s);if(s[0] == 'c') {printf("%d\n", max(a[1].up[0][0], max(a[1].up[0][1], a[1].up[1][1])));} else {int L, R;scanf("%d%d", &L, &R);update(L, R, 1, n, 1);}}return 0;
}/*
*/