#import <stdio.h>
typedef long long INT;
int main(){
    INT x;
    scanf("%lld",&x);
    INT n = x/11;
    INT r = x%11;
    INT ans;
    if(r==0){
        ans = 2*n;
    } else if (r<=6){
        ans = 2*n+1;
    } else {
        ans = 2*n+2;
    }
    printf("%lld",ans);
}
