#include <iostream> #include <cstdio> #include <cmath> using namespace std; int main(){ int h1,h2,m1,m2,h,m,sum1,sum2,sum,k; while(~scanf("%d:%d%d:%d",&h1,&m1,&h2,&m2)){ k=0; sum1=h1*60+m1; sum2=h2*60+m2; for(int i=sum1;i<=sum2;i++){ h=i/60; m=i%60; sum=h*2500+m; int flag=1; for(int j=2;j<=sqrt(sum);j++){ if(sum%j==0){ flag=0; break; } } if(flag==1) k++; } printf("%d\n",k); } return 0; } |
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