
function Main(_input) {
    var input = _input.split(" ");
    var num_A = parseInt(input[0]);
    var num_B = parseInt(input[1]);
    var num_N = parseInt(input[2]);
    var num_MaxVal = num_A <= num_B? num_A - 1 : num_B - 1;
    var result = 0;
    for( var x = 0 ; x <= num_N; x++ ) {
        y = parseInt(num_A * x / num_B) - num_A * parseInt( x / num_B );
        console.log(y);
        result = result < y? y:result;
        if( result == num_MaxVal ) break;
    }
    console.log(result);
}
Main(require("fs").readFileSync("/dev/stdin", "utf8"));