//#include <bits/stdc++.h>
#include<iostream>
#include<cstdio>
#include<string>
#include<algorithm>
#include<vector>
#include<stack>
#include<queue>
#define FOR(i,a,b) for(int i=(a);i<(b);i++)
#define REP(i,n) FOR(i,0,n)
#define pb push_back
#define INF 93193111451418101
#define MIN -93193111451418101
using namespace std;
typedef long long ll;//int64
typedef unsigned long long ull;
ll gcd(ll a,ll b){return b?gcd(b,a%b):a;}
int dx[4]={1,0,-1,0};
int dy[4]={0,1,0,-1};
//----------program from here----------


int main(){
    ll s1=0;
    ll s2=0;
    
    ll N=1000000007,N2;
    N-=7;
    cin>>N2;
    for(int i=0;;i++){
      N/=10;
      s1++;
      if(N==1)break;
    }

    N2-=7;
    for(int i=0;;i++){
      N2/=10;
      s2++;
      if(N2==1)break;
    }
    cout<<abs(s2-s1)<<endl;



    return 0;
}