Monistus

input/code.cpp: In function 'int main()':
input/code.cpp:10:29: error: 'sing' was not declared in this scope
   10 |         for (int i = 0; i < sing(input.length()); i++)
      |                             ^~~~

#include <iostream>
using namespace std;

int main()
{
    string input;
    cin >> input;
    while (input.find_first_of("1234567890") != string::npos)
    {
        for (int i = 0; i < sing(input.length()); i++)
        {
            if (input[i] >= '0' and input[i] <= '9')
            {
                char c = input[i];
                input.erase(i, 1);
                input.insert(i, input, i, c - '0');
            }
        }
    }

    cout << input << endl;
}