function licenaneshto(input){

    let shape = input.shift();
    let area = 0;

    if (shape === 'square')
    {
    let side = Number(input.shift());
            console.log(side*side);
    }

        else if (shape === 'rectangle')
        {
        let sideA = Number(input.shift());
        let sideB = Number(input.shift());

        console.log(sideA*sideB);}

        else if (shape === 'circle')
       {
           let r = Number(input.shift());
        console.log(Math.PI*r*r) }
        else if (shape === 'triangle')

        {
            let ha = Number(input.shift());
        let a = Number(input.shift());
        console.log((a*ha)/2);
        }

}


licenaneshto([
    `triangle`,
    5,
    4
])