#include <bits/stdc++.h>
using namespace std;
char string_in_buffer[(int)2e6];
void fast_scan(int &first) { scanf("%d", &first); }
void fast_scan(long long &first) { scanf("%lld", &first); }
void fast_scan(unsigned long long &first) { scanf("%llu", &first); }
void fast_scan(double &first) { scanf("%lf", &first); }
void fast_scan(long double &first) { scanf("%Lf", &first); }
void fast_scan(char &first) {
  scanf("%c", &first);
  if (first == '\n') {
    fast_scan(first);
  }
}
void fast_scan(string &first) {
  scanf("%s", string_in_buffer);
  first = string(string_in_buffer);
}
template <class TFirst, class TSecond>
void fast_scan(pair<TFirst, TSecond> &p) {
  fast_scan(p.first);
  fast_scan(p.second);
}
template <class T>
void fast_scan(vector<T> &v) {
  for (auto &first : v) fast_scan(first);
}
void fast_print(const int &first) { printf("%d", first); }
void fast_print(const unsigned int &first) { printf("%u", first); }
void fast_print(const long long &first) { printf("%lld", first); }
void fast_print(const unsigned long long &first) { printf("%llu", first); }
void fast_print(const double &first) { printf("%.15lf", first); }
void fast_print(const long double &first) { printf("%.15Lf", first); }
void fast_print(const char &first) { printf("%c", first); };
void fast_print(const string &first) { printf("%s", first.c_str()); }
void fast_print(const char v[]) { fast_print((string)v); }
template <class TFirst, class TSecond>
void fast_print(const pair<TFirst, TSecond> &p) {
  fast_print(p.first);
  fast_print(' ');
  fast_print(p.second);
}
template <class T>
void fast_print(const vector<T> &v) {
  if (v.empty()) return;
  fast_print(v[0]);
  for (int i = 1; i < v.size(); i++) {
    fast_print(' ');
    fast_print(v[i]);
  }
}
template <class T>
void fast_print(const vector<vector<T>> &v) {
  if (v.empty()) return;
  fast_print(v[0]);
  for (int i = 1; i < v.size(); i++) {
    fast_print('\n');
    fast_print(v[i]);
  }
}
template <class T>
void fast_print(const T &v) {
  for (const auto &first : v) {
    fast_print(first);
    fast_print(' ');
  }
}
using namespace std;
namespace smart_io {
string print_start = "";
string sep = " ";
bool first_print = false;
void precall_print() {
  fast_print(print_start);
  print_start = "\n";
  first_print = true;
}
void _print(deque<string>) {}
template <class T, class... Args>
void _print(deque<string> names, T elem, Args... args) {
  if (!first_print) {
    fast_print("\n");
  } else {
    first_print = false;
  }
  fast_print(names.front());
  fast_print(" = ");
  fast_print(elem);
  names.pop_front();
  _print(names, args...);
}
}  // namespace smart_io
template <class T>
ostream &operator,(ostream &os, const T &object) {
  if (!smart_io::first_print) {
    fast_print(smart_io::sep);
  } else {
    smart_io::first_print = false;
  }
  fast_print(object);
  return os;
}
template <class T>
istream &operator,(istream &is, T &object) {
  fast_scan(object);
  return is;
}
namespace typedefs {}
namespace numbers_operation {
template <class T>
T floor_mod(T a, T b) {
  if (a % b == 0) return 0;
  if (a >= 0 && b >= 0) return a % b;
  if (a <= 0 && b <= 0) return a % b;
  return abs(b) - (abs(a) % abs(b));
}
}  // namespace numbers_operation
using namespace numbers_operation;
using namespace typedefs;
map<char, int> id = {make_pair('R', 0), make_pair('S', 1), make_pair('P', 2)};
int fri(int first) { return (first + 1) % 3; }
int enemy(int first) { return (first - 1 + 3) % 3; }
const int N = 3e5;
struct Fen {
  vector<int> T;
  Fen() { T.resize(N); }
  int get(int i) {
    int r = 0;
    for (; i > -1; i = (i & (i + 1)) - 1) {
      r += T[i];
    }
    return r;
  }
  int query(int l, int r) {
    if (l >= r) return 0;
    return get(r - 1) - get(l - 1);
  }
  void inc(int i, int d) {
    for (; i < N; i = (i | (i + 1))) {
      T[i] += d;
    }
  }
};
vector<set<int>> pos(3);
vector<Fen> fen(3);
void add(int t, int p) {
  fen[t].inc(p, 1);
  pos[t].insert(p);
}
void rem(int t, int p) {
  fen[t].inc(p, -1);
  pos[t].erase(p);
}
int calc(int t) {
  if (pos[enemy(t)].empty()) return ((int)pos[t].size());
  if (pos[fri(t)].empty()) return 0;
  int enF = *pos[enemy(t)].begin();
  int enE = *pos[enemy(t)].rbegin();
  int fiF = *pos[fri(t)].begin();
  int fiE = *pos[fri(t)].rbegin();
  int rez = fen[t].query(0, min(fiE, enF));
  rez += fen[t].query(max(fiF, enE), N);
  rez += fen[t].query(max(fiF, enF), min(fiE, enE));
  return rez;
}
int n, q;
signed main(signed argc, char *argv[]) {
  cin, n, q;
  string s;
  cin, s;
  for (int i = 0; i < (n); i++) {
    add(id[s[i]], i);
  }
  smart_io::precall_print();
  cout, calc(0) + calc(1) + calc(2);
  for (int i = 0; i < (q); i++) {
    string symb;
    int j;
    cin, j, symb;
    j--;
    rem(id[s[j]], j);
    s[j] = symb[0];
    add(id[s[j]], j);
    smart_io::precall_print();
    cout, calc(0) + calc(1) + calc(2);
  }
}
