#include<iostream> #include<math.h> using namespace std; bool isprime(int x){ for(int i=2;i<=x/2;i++){ if(x%i==0)return false; } return true; } int main(){ int h1,m1,s1,h2,m2,s2; char a,b; while(cin>>h1>>a>>m1>>h2>>b>>m2){ s1=h1*2500+m1; s2=h2*2500+m2; int k=0; for(int i=s1;i<=s2;i++){ if(isprime(i)) k++; } cout<<k<<endl; } return 0; } |
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