let input = require('fs').readFileSync('/dev/stdin', 'utf8')
// let input = require('fs').readFileSync('./sample.txt', 'utf8')
.split(/\n| /)
// .map(item => parseInt(item))
.slice(0,-1)

const [N, X, time] = input.map(item => parseInt(item))


let total = 0
let total_t = 0
while(true){
    if(total >= N){
        console.log(total_t)
        return
    }
    total += X
    total_t += time
}