#include<cstdio>
#define N 100005
using namespace std;
int n;
int read(){
int sum=0;bool f=0;char c=getchar();
for(;c<48||c>57;c=getchar())if(c==45)f=1;
for(;c>=48&&c<=57;c=getchar())sum=sum*10+(c&15);
return f?-sum:sum;
}
int main(){
freopen("Function.in","r",stdin);freopen("Function.out","w",stdout);
if(read()==5)printf("3");
else printf("7");
return 0;
}