#include <iostream>
#include <string>
#include <vector>

using namespace std;

int main()
{
    int n, q;
    string s;
    cin >> n >> s >> q;
    // map<char, int> count;
    vector<int> positions;
    int pos = 0, count = 0;
    while ((pos = s.find("PSU", pos)) != string::npos) {
        ++count;
        positions.push_back(pos);
        pos += 3;
    }
    cout << count << endl;
    char ch;
    for (int i = 0; i < q; i++)
    {
        cin >> pos >> ch;
        pos--;
        bool a = false, b = false, c = false;
        if (pos - 2 >= 0)
        {
            if (s.substr(pos - 2, 3) == "PSU")
                a = true;
            // cout << 0 << s.substr(pos - 2, 3) << endl;
        }
        if (pos - 1 >= 0)
        {
            if (s.substr(pos - 1, 3) == "PSU")
                b = true;
            // cout << 1 << s.substr(pos - 1, 3) << endl;
        }
        if (s.substr(pos, 3) == "PSU")
            c = true;
        // cout << 2 << s.substr(pos, 3) << endl;
        // cout << "CHANGE" << endl;
        s[pos] = ch;
        if (pos - 2 >= 0)
        {
            // cout << s.substr(pos - 2, 3) << endl;
            if (s.substr(pos - 2, 3) == "PSU" && !a)
                count++;
            else if (s.substr(pos - 2, 3) != "PSU" && a)
                count--;
        }
        if (pos - 1 >= 0)
        {
            // cout << s.substr(pos - 1, 3) << endl;
            if (s.substr(pos - 1, 3) == "PSU" && !b)
                count++;
            else if (s.substr(pos - 1, 3) != "PSU" && b)
                count--;
        }
        // cout << 2 << s.substr(pos, 3) << endl;
        if (s.substr(pos, 3) == "PSU" && !c)
            count++;
        else if (s.substr(pos, 3) != "PSU" && c)
            count--;
        // cout << s << endl;
        cout << count << endl;
    }
}