"use strict"

const arg_str = require('fs').readFileSync('/dev/stdin', 'UTF-8').split(' ')
const a = arg_str[0]
const b = arg_str[1]
const x = arg_str[2]

if(x <= (1/2)*a*a*b){
    const rad = Math.atan(a*b*b/2/x)
    console.log(rad * 180 / Math.PI)
}else{
    const rad = Math.atan(2/a/a/a*(a*a*b-x))
    console.log(rad * 180 / Math.PI)
}

