function Main(input){
  
  var str = input.trim().split("\n");
  var n = parseInt(str[0],10);
  var s = str[1];

  var targetStr = "#." ;

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