View Code of Problem 120

 #include<bits/stdc++.h>
using namespace std;
int isSu(int s){
	if(s==1) return 0;
	int flag=1;
	for(int i=2;i<=sqrt(s);i++){
		if(s%i==0){
			flag=0;
			break;
		} 
	}
	return flag;
}

int main(){
	int h1,m1,h2,m2,h,m,s,k;
	while(scanf("%d:%d",&h1,&m1)!=EOF){
		scanf("%d:%d",&h2,&m2);
		int sum1=h1*60+m1;
		int sum2=h2*60+m2;
		int cnt=0;
		for(int i=sum1;i<=sum2;i++){
			h=i/60;
			m=i%60;
			s=h*2500+m;
			if(isSu(s)==1) cnt++;
		}
		cout<<cnt<<endl;
	}
}