#include<stdio.h>
#include<stdlib.h>
#include<stdint.h>
#include<inttypes.h>

typedef int32_t i32;

void run (void) {
  i32 n;
  scanf ("%" SCNi32, &n);
  char *s = (char *) calloc (n + 1, sizeof (char));
  scanf ("%s", s);
  i32 ans = 0;
  for (i32 d = 1; d < n; ++d) {
    for (i32 i = 0; i + 2 * d < n; ++i) {
      if (s[i] =='U' && s[i + d] == 'M' && s[i + 2 * d] == 'G') {
	ans++;
      }
    }
  }
  printf ("%" PRIi32 "\n", ans);
}

int main (void) {
  run ();
  return 0;
}