function processData(input) {
    //Enter your code here
    var n = input.split("\n");
    var steps = n[1];
    n = parseInt(n[0], 10);

    var i = 0;
    var c = 0;
    var h = 0;
    for (; i < n; i++) {
        if (steps[i] === "D") {
            h--;
            if (h === -1) {
                c++;
            }
        } else {
            h++;
        }
    }
    console.log(c);
} 

process.stdin.resume();
process.stdin.setEncoding("ascii");
_input = "";
process.stdin.on("data", function (input) {
    _input += input;
});

process.stdin.on("end", function () {
   processData(_input);
});