P1179 [NOIP2010 普及组] 数字统计

// Problem: P1179 [NOIP2010 普及组] 数字统计
// Contest: Luogu
// URL: https://www.luogu.com.cn/problem/P1179
// Memory Limit: 125 MB
// Time Limit: 1000 ms
// User: Pannnn

#include <bits/stdc++.h>

using namespace std;

int main() {
    int l, r;
    cin >> l >> r;
    long long cnt = 0;
    for (int i = l; i <= r; ++i) {
        int t = i;
        while (t) {
            if (t % 10 == 2) {
                ++cnt;
            }
            t /= 10;
        }
    }
    cout << cnt << endl;
    return 0;
}