View Code of Problem 120

#include <iostream>
#include <cstdio>
#include <cmath>
using namespace std;
int main(){
    int a1,b1,a2,b2,sum,m1,m2,n1,n2,flag=1,k=0;
    while(~scanf("%d:%d%d:%d",&a1,&a2,&b1,&b2)){
        flag=1,k=0;
        m1=a1*60+a2;
        n1=b1*60+b2;
        for(int i=m1;i<=n1;i++){
            flag=1;
            m2=i/60;
            n2=i%60;
            sum=m2*2500+n2;
            for(int i=2;i<=sqrt(sum);i++){
                if(sum%i==0)
                    flag=0;
                
            }
            if(flag==1)
                k++;
        }
        cout<<k<<endl;
    }
    
    return 0;
}