#include <stdio.h>
#include <stdlib.h>
#include <stdbool.h>

bool isIOI(char* str, int index);

int main(){
    int N, M;
    scanf("%d %d\n",&N,&M);

    char* S = (char*)malloc(M+1);
    fgets(S, M+1, stdin);

    int oiCount = 0, result = 0, i = 0;
    while(i<M-1){
        if(isIOI(S,i)){
            oiCount++;
            i += 2;

            if(oiCount==N){
                result++;
                oiCount--;
            }
        }
        else{
            oiCount = 0;
            i++;
        }

    }

    printf("%d\n",result);

    free(S);
    return 0;
}

bool isIOI(char* str, int index){
    return (str[index] == 'I' && str[index+1] == 'O' && str[index+2] == 'I') ? true : false;
}