1538F - Interesting Function - CodeForces Solution

#include <bits/stdc++.h>
using namespace std;
typedef long long ll;

void pre() {
    ios::sync_with_stdio(false);
    cin.tie(0);
    cout.tie(0);
}

int cnt(int x) {
    int ans = 0;
    while (x) {
        ans += x;
        x /= 10;
    }
    return ans;
}
void solve() {
    int l, r;
    cin >> l >> r;
    int ans = cnt(r) - cnt(l);
    cout << ans << endl;
}
int main() {
    pre();
    int t;
    cin >> t;
    while (t--) {
        solve();
    }
}