delete pics to save space

history_source/信息学奥赛一本通/1.6.1.2t.cpp

@@ -0,0 +1,18 @@
+#include<cstdio>
+using namespace std;
+bool isp(int n)
+{
+	if(!n&1) return 0;
+	for(int i=2;i*i<=n;i++) if(n%i==0) return 0;
+	return 1;
+}
+int main()
+{
+	int ans=1;
+	int n;
+	scanf("%d",&n);
+	for(int i=3;i<=n;i++) ans+=isp(i);
+	printf("%d\n",ans);
+	return 0;
+}
+