920

//920
#include <cstdio>

char s[101];
int n;

int main(void) {
    FILE* fin = fopen("input.txt", "r");
    FILE* fout = fopen("output.txt", "w");

    fscanf(fin, "%d%s", &n, s);
    fclose(fin);
    int x = 0, out = 0;
    for (int i = 0; i < n; ++ i) {
        if (s[i] == 'x')
            ++ x;
        else if (x > 2) {
            out += x - 2;
            x = 0;
        }
        else
            x = 0;
    }
    if (x > 2)
        out += x - 2;

    fprintf(fout, "%d\n", out);
    fclose(fout);
    return 0;
}