1 #define IOS ios_base::sync_with_stdio(0); cin.tie(0);
2 #include <cstdio>//sprintf islower isupper
3 #include <cstdlib>//malloc exit strcat itoa system("cls")
4 #include <iostream>//pair
5 #include <fstream>//freopen("C:\\Users\\13606\\Desktop\\Input.txt","r",stdin);
6 #include <bitset>
7 //#include <map>
8 //#include<unordered_map>
9 #include <vector>
10 #include <stack>
11 #include <set>
12 #include <string.h>//strstr substr strcat
13 #include <string>
14 #include <time.h>// srand(((unsigned)time(NULL))); Seed n=rand()%10 - 0~9;
15 #include <cmath>
16 #include <deque>
17 #include <queue>//priority_queue<int, vector<int>, greater<int> > q;//less
18 #include <vector>//emplace_back
19 //#include <math.h>
20 #include <cassert>
21 #include <iomanip>
22 //#include <windows.h>//reverse(a,a+len);// ~ ! ~ ! floor
23 #include <algorithm>//sort + unique : sz=unique(b+1,b+n+1)-(b+1);+nth_element(first, nth, last, compare)
24 using namespace std;//next_permutation(a+1,a+1+n);//prev_permutation
25 //******************
26 clock_t __START,__END;
27 double __TOTALTIME;
28 void _MS(){__START=clock();}
29 void _ME(){__END=clock();__TOTALTIME=(double)(__END-__START)/CLOCKS_PER_SEC;cout<<"Time: "<<__TOTALTIME<<" s"<<endl;}
30 //***********************
31 #define rint register int
32 #define fo(a,b,c) for(rint a=b;a<=c;++a)
33 #define fr(a,b,c) for(rint a=b;a>=c;--a)
34 #define mem(a,b) memset(a,b,sizeof(a))
35 #define pr printf
36 #define sc scanf
37 #define ls rt<<1
38 #define rs rt<<1|1
39 typedef pair<int,int> PII;
40 typedef vector<int> VI;
41 typedef long long ll;
42 const double E=2.718281828;
43 const double PI=acos(-1.0);
44 const ll INF=(1LL<<60);
45 const int inf=(1<<30);
46 const double ESP=1e-9;
47 const int mod=(int)1e9+7;
48 const int N=(int)3e6+10;
49
50 int prime[N];
51 ll phi[N];
52 bool unprime[N];
53
54 ///O(NloglogN)，推荐
55 void phi_table()
56 {
57 int i, j;
58 for (i = 2; i < N; ++i)
59 if (!phi[i])
60 for (j = i; j < N; j += i)
61 {
62 if (!phi[j]) phi[j] = j;
63 phi[j] -= phi[j] / i; ///简化后的代码
64 }
65 }
66
67 ///O(N)
68 void linear_phi_table2()
69 {
70 int i, j, k = 0;
71 for (i = 2; i < N; i++)
72 {
73 if (!unprime[i]) ///若i为素数，phi(i)=i-1
74 {
75 prime[k++] = i;
76 phi[i] = i - 1;
77 }
78 for (j = 0; j < k && prime[j] * i < N; j++)
79 {
80 unprime[prime[j] * i] = true;
81 if (i % prime[j]) ///若i和p互素，则phi(i*p) = phi(i) * phi(p) = phi(i) * (p-1)
82 phi[prime[j] * i] = phi[i] * (prime[j] - 1);
83 else
84 {
85 ///此时有i=kp，则
86 ///phi(p*kp) = phi(k*p^2) = p*phi(kp)
87 phi[prime[j] * i] = phi[i] * prime[j];
88 break;
89 }
90 }
91 }
92 }
93
94 int main()
95 {
96 int a,b;
97 linear_phi_table2();
98 for(int i=2;i<=3000010;++i)
99 phi[i]+=phi[i-1];
100 while(~sc("%d%d",&a,&b))
101 {
102 pr("%lld\n",phi[b]-phi[a-1]);
103 }
104 return 0;
105 }
106
107 /**************************************************************************************/
