5525.cpp

#include <iostream>
#include <stdio.h>
#include <memory.h>
#include <vector>
#include <map>
#include <set>
#include <queue>
#include <stack>
#include <string>
#include <algorithm>

using namespace std;

int main()
{
    int n, m;
    cin >> n >> m;

    string str;
    cin >> str;

    int nowk = 0;
    int count = 0;
    int idx = 0;

    while (idx < m)
    {
        if (nowk == 0)
        {
            if (str.substr(idx, 3) == "IOI")
            {
                nowk++;
                idx += 2;
            }
            idx++;
            continue;
        }

        if (str.substr(idx, 2) == "OI")
        {
            nowk++;
            idx += 2;
            continue;
        }

        count += max(0, nowk - n + 1);
        nowk = 0;
    }

    count += max(0, nowk - n + 1);

    cout << count << "\n";

    return 0;
}