process.stdin.resume();
process.stdin.setEncoding('utf8');
    var map=[];
    map[0] = Array.from('qwertyuiop')
    map[1] = Array.from('asdfghjkl')
    map[2] = Array.from('zxcvbnm')
function isAdj(a,b){
    var posAR,posAC;
    [0,1,2].forEach(function(itemR,index,arr){
        if(map[itemR].indexOf(a)!=-1){
            posAR=itemR
            posAC=map[itemR].indexOf(a)
        }
    })
    var posBR,posBC;
    [0,1,2].forEach(function(itemR,index,arr){
        if(map[itemR].indexOf(b)!=-1){
            posBR=itemR
            posBC=map[itemR].indexOf(b)
        }
    })
    var q1=(Math.abs(posAR-posBR)<=1 && posAC-posBC==0)
    var q2=(Math.abs(posAC-posBC)<=1 && posAR-posBR==0)
    return q1 || q2
}
var arrLeft = Array.from('qwertasdfgzxcvb')

process.stdin.on('data', function (chunk) {
    var line = chunk.toString();
    var mistake = 0
    var arrInput = Array.from(line)
    var prevHand = -1 //0=left
    arrInput.forEach(function(item, index, arr){
        var currentHand
        if(index!=0 && isAdj(arr[index],arr[index-1])){

            currentHand = prevHand
            if(arrLeft.indexOf(item)!=-1){//should be left
                if(currentHand==1){
                    mistake++
                }
            }else{
                if(currentHand==0){
                    mistake++
                }
            }
        }else{
            if(arrLeft.indexOf(item)!=-1){
                currentHand = 0
            }else{
                currentHand = 1
            }
        }

        prevHand=currentHand
    });
    console.log(mistake)
});