Cod sursă (job #470176)

#include <stdio.h>
#include <fstream>
#include <bits/stdc++.h>
using namespace std;
 
ifstream fin("prob.in");
ofstream fout("prob.out");

int c,t,m,x, k,d=0,s=0,minn,val,p;

int divv(int a, int b){  
    int s;
	s=a/b;
    if(b*s<a) s++;
    return s;
}

int main (){
    fin>>c>>t>>m>>x;
    minn=divv(x,m);
    val=minn; d=divv(c,m); s=m*d;
	k=1;
while(s<=x && s-c+k*m*t<=x && val<=minn){
        minn=val; s-=c;
        d+=t; s+=k*m*t;
        k++;
        val=d+divv(x-s,k*m);
        if(s<c){ p=divv(c-s,k*m);
                 s+=k*m*p;
                 d+=p;
              }
    } 
	minn=min(minn, val);
     fout<<minn;
    return 0;
}