function Main(input) {
	input = input.split("\n");
	const n = parseInt(input[0]);

	var text = input[1];

	var targetStr = "#." ;

	var count = ( text.match( new RegExp( targetStr, "g" ) ) || [] ).length ;
	console.log(count);
}
Main(require("fs").readFileSync("/dev/stdin", "utf8"));