CodeForces 546D(질량 계수 표기법)

Description Two soldiers are playing a game. At the beginning first of them chooses a positive integer n and gives it to the second soldier. Then the second one tries to make maximum possible number of rounds. Each round consists of choosing a positive integer x > 1, such that n is divisible by x and replacing n with n / x. When n becomes equal to 1 and there is no more possible valid moves the game is over and the score of the second soldier is equal to the number of rounds he performed.
To make the game more interesting, first soldier chooses n of form a! / b! for some positive integer a and b (a ≥ b). Here by k! we denote the factorial of k that is defined as a product of all positive integers not large than k.
What is the maximum possible score of the second soldier?
Input First line of input consists of single integer t (1 ≤ t ≤ 1 000 000) denoting number of games soldiers play.
Then follow t lines, each contains pair of integers a and b (1 ≤ b ≤ a ≤ 5 000 000) defining the value of n for a game.
Output For each game output a maximum score that the second soldier can get.
Sample Input Input 2 3 1 6 3 Output 2 5
**제목: **a!/b! 뒤에 있는 숫자를 최대 몇 개까지 빼야 1에 도달할 수 있느냐고 물었을 때 상질인자로 표를 쳐야 한다~~~, 접두사와

#include 
#include 
#define M 5000050
#define LL long long

bool isprime[M];
LL num[M];

void bymeter()
{
    memset(num, 0, sizeof(num));
    memset(isprime, true, sizeof(isprime));
    isprime[1] = false;
    for(int i=2; i//     
    {
        if(isprime[i])
        {
            for(int j=i; jint temp = j;
                while(temp % i == 0)
                {
                    temp /= i;
                    num[j]++;
                }
                isprime[j] = false;
            }
        }
    }
    for(int i=1; i//    
    {
        num[i] += num[i-1];
    }

}
int main()
{
    int t, a, b;
    scanf("%d", &t);
    bymeter();
    while(t--)
    {
        scanf("%d%d", &a, &b);
        printf("%lld
", num[a] - num[b]);
    }


    return 0;
}