# /usr/bin/python
# -*- coding: utf-8 -*-
#
import sys
 
 
N = int(input())
S = "A" + str(input())

ans=0
for i in range(1,N-1):
  if S[i] != 'U':
    continue
  for j in range(1,(N-i)//2+1):
    if (S[i+j]=='M') and (S[i+2*j]=='G'):
      ans += 1
print(ans)