how to convert the last 2 chars in a string to an int

int convert(string s){
    int result = 0;
    for (int i = s.size() - 2; i < s.size(); i++) {
        result = result * 10 + s[i] - '0';
    }
    return result;
}
 
int main() {
    string s = "abc123";
    cout<<convert(s)<<endl;
    return 0;
}