function processData(input) {
    var altitude = 0,
        down = false,
        valleys = 0;
    for (var i = 0; i < input.length; i++) {
        if (input[i] === 'U') {
            altitude++;
            if (altitude === 0 && down) valleys++;
        }
        else if (input[i] === 'D') {
            if (altitude === 0) down = true;
            altitude--;
        }
    };
    console.log(valleys);
} 

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

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