23 lines
504 B
C++
23 lines
504 B
C++
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#include <bits/stdc++.h>
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using namespace std;
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int cnt;
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bool check(int x) {
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string s = to_string(x);
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string t = s;
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reverse(t.begin(), t.end());
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if (s != t) return false;
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bool flag = false;
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for (int i = 0; i < s.size(); i++)
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if (s[i] == '7') flag = true;
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if (!flag) return false;
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return true;
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}
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int main() {
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int a, b;
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cin >> a >> b;
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for (int i = a; i <= b; i++)
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if (check(i)) cnt++;
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cout << cnt << endl;
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return 0;
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}
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