declare var require: any;
let lines: string[] = require("fs").readFileSync("/dev/stdin", "utf8").split("\n");
let S = lines[1];
S = S.replace(/CPCTCPC/g, 'CPCTF');

let ans = 0;
while (true) {
	const index = S.indexOf('CPCTF');
	if (index === -1) break;
	S = S.slice(index + 5);
	ans++;
}
console.log(ans);