1 /************************************************************** 2     Problem: 2134 3     User: rausen 4     Language: C++ 5     Result: Accepted 6     Time:1292 ms 7     Memory:78932 kb 8 ****************************************************************/ 9  10 #include <cstdio>11 #include <cmath>12  13 using namespace std;14 typedef double lf;15 typedef long long ll;16 const int N = 10000005;17 const ll Mod = 100000001;18 ll n, a, b, c, d[N];19  20 inline int read() {21     int x = 0;22     char ch = getchar();23     while (ch < ‘0‘ || ‘9‘ < ch)24         ch = getchar();25     while (‘0‘ <= ch && ch <= ‘9‘) {26         x = x * 10 + ch - ‘0‘;27         ch = getchar();28     }29     return x;30 }31  32 int main() {33     int i;34     n = read(), a = read(), b = read(), c = read();35     for (d[1] = read(), i = 2; i <= n; ++i)36         d[i] = (d[i - 1] * a + b) % Mod;37     for (i = 1; i <= n; ++i)38         d[i] = (d[i] % c) + 1;39     d[n + 1] = d[1];40     lf ans = 0;41     for (i = 1; i <= n; ++i)42         if (d[i] <= d[i + 1])43             ans += (lf) 1.0 / d[i + 1];44         else45             ans += (lf) 1.0 / d[i];46     printf("%.3lf", ans);47     return 0;48 }