820A - Mister B and Book Reading - CodeForces Solution

#include<bits/stdc++.h>
using namespace std;

int main(){
	int n, v0, v1, a, l;
	cin >> n >> v0 >> v1 >> a >> l;
	
	int ans = 1, lp = v0;
	
	while(lp < n){
		ans++;
		lp += min(v0+a*(ans-1), v1) - l;
	}
	cout << ans << endl;
}