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#include <iostream>
#include <vector>

using namespace std;
using ll = long long;

int main()
{
    cin.tie(0)->sync_with_stdio();
    string a, b, c;
    cin>>a>>b>>c;
    ll res = 0;
    int cur = 0;
    bool of = 0;
    for(int i=a.size() - 1; i >= 0; i--) {
        if(a[i] + b[i] + of == c[i] + '0') {
            of = 0;
            res += ++cur;
        } else if (a[i] + b[i] + of == c[i] + '0' + 10) {
            of = 1;
        } else if(a[i] + b[i] == c[i] + '0') {
            cur = 1;
            of = 0;
            ++res;
        } else if(a[i] + b[i] == c[i] + '0' + 10) {
            cur = 0;
            of = 1;
        } else {
            cur = 0;
            of = 0;
        }
    }
    cout<<res<<"\n";
}