5525.py

import sys
input = sys.stdin.readline

n = int(input().strip())
t = int(input().strip())
arr = input().strip()

# target = 'I'
# for _ in range(n):
#   target += 'OI'

# cnt = 0
# idx = 0
# while idx < t - 2 * n - 1:
#   if arr[idx:idx + 2*n + 1] == target:
#     cnt += 1
#     idx += 2
#   else:
#     idx += 1

cnt = 0
idx = 0
part = 0

while idx < (t - 2):
  if arr[idx] == 'I' and arr[idx + 1] == 'O' and arr[idx + 2] == 'I':
    part += 1
    if part == n:
      cnt += 1
      part -= 1
    idx += 1
  else:
    part = 0
  idx += 1

print(cnt)