# include<stdio.h> # include<math.h> int f(int i) { int t,flag = 0; for(t=2;t<=sqrt(i);++t) { if(i%t==0) { flag = 1; break; } } if(flag) { return 0; } else return 1; } int main(void) { int h,m,i,H,M,cnt=0; while(scanf("%2d:%2d",&h,&m)!=EOF) { scanf("%2d:%2d",&H,&M); int sum = 0; sum = (H*60+M)-(h*60+m); for(i=0;i<=sum;++i) { if(m>=60) { m = m-60; ++h; } if(f(h*2500+m)) { ++cnt; } ++m; } printf("%d",cnt); } return 0; } |
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