Submission #1605751

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Source Code Expand

#include <bits/stdc++.h>
using namespace std;
#define FOR(i, n) for(int i = 0; i < (n); i++)
#define MEM(a, x) memset(a, x, sizeof(a))
#define ALL(a) a.begin(), a.end()
#define UNIQUE(a) a.erase(unique(ALL(a)), a.end())
typedef long long ll;

ll a, b;

ll f(ll x) {
	string s = to_string(x);
	int n = s.size();
	ll ret = 0;
	FOR(i, n) {
		if (i == n-1) {
			if (s[i] <= '4') ret += min(4, s[i]-'0'+1);
			else ret += min(8, s[i]-'0');
			break;
		}
		if (s[i] == '0') continue;
		ll it = s[i]-'0';
		if (s[i] > '4') it--;
		it *= pow(8, n-1-i);
		ret += it;
		if (s[i] == '4' || s[i] == '9') break;
	}
	return x+1-ret;
}

int main(int argc, char const *argv[]) {
	ios_base::sync_with_stdio(false);
	cin >> a >> b;
	cout << f(b)-f(a-1) << endl;
	return 0;
}

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