View Code of Problem 120

#include <stdio.h>
#include <math.h>
int isp(int n){
	if(n<=1) return 0;
	int i;
	for(i=2;i<=sqrt(n);i++) 
		if(n%i==0) return 0;
	return 1;	
} 
int main(){
	int n,h1,m1,h2,m2,c=0,i,j;
	while(scanf("%2d:%2d",&h1,&m1)!=EOF){
		scanf("%2d:%2d",&h2,&m2);
		c=0;
		if(h2-h1==0) {
			for(i=m1;i<=m2;i++)
				if(isp(i)) c++;
		}
			
		else {
			for(i=m1;i<=59;i++) 
				if(isp(h1*2500+i)) c++;
			for(i=0;i<m2;i++) 
			 if(isp(h2*2500+i)) c++;
			if(h2-h1>=2)
				for(i=h1+1;i<h2;i++)
					for(j=0;j<=59;j++)
						if(isp(i*2500+j)) c++;
		}
		printf("%d\n",c);
	}
	return 0;
}

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