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#include <bits/stdc++.h>
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using namespace std;
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int main() {
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int L, R, count = 0;
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cin >> L >> R;
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for (int i = L; i <= R; i++) {
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string a = to_string(i); //注意数字转字符串的办法
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for (char c : a) { //注意遍历字符串的方法
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if (c == '2')
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count++;
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}
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}
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cout << count << endl;
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return 0;
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}
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