function metricConverter(input) {
    let num = Number(input.shift());
    let inputMetric = input.shift();
    let output = input.shift();
    let result = 0.0;

    if (inputMetric == "mm" && output == "m") {
        result = num / 1000;
    } else if (inputMetric == "mm" && output == "cm")  {
        result = num / 10;
    } else if (inputMetric == "cm" && output == "mm") {
        result = num * 10;
    } else if (inputMetric == "cm" && output == "m") {
        result = num / 100
    } else if (inputMetric == "m" && output == "mm") {
        result = num*1000;
    } else if (inputMetric == "m" && output == "cm") {
        result = num*100;
    }
    console.log((result).toFixed(3));
}