function processData(input) {
    var arr = input.match(/[0-9]/g);
    var calcAB = (0.5*arr[2]*arr[0])+(0.5*arr[2]*arr[1]);
    var rtn = calcAB % (Math.pow(10,9)+7);
    
    console.log(rtn);
    //Enter your code here
} 

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

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