CodeForces

//水题#include <bits/stdc++.h>using namespace std;int main(){int c, v0, v1, a, l;while (cin >> c >> v0 >> v1 >> a >> l){int day = 0;if (v0 >= c){cout << 1 << endl;continue;}day++; c -= v0;int flag = 1;while (1){c += l;v0 += a;if (v0 > v1) v0 = v1;if (v0 >= c){flag = 0;cout << ++day;break;}c -= v0; day++;}if (!flag) continue;else cout << day << endl;}return 0;}