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#include <bits/stdc++.h>
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using namespace std;
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bool cmp(vector<int>& A, vector<int>& B) {
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    if (A.size() != B.size()) return A.size() > B.size();
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    for (int i = A.size() - 1; i >= 0; i--) {
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        if (A[i] != B[i]) return A[i] > B[i];
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    }
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    return true;
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}
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vector<int> sub(vector<int>& A, vector<int>& B) {
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    vector<int> C;
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    int t = 0;
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    for (int i = 0; i < (int)A.size(); i++) {
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        t = A[i] - t;
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        if (i < (int)B.size()) t -= B[i];
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        C.push_back((t + 10) % 10);
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        if (t < 0) t = 1;
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        else t = 0;
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    }
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    while (C.size() > 1 && C.back() == 0) C.pop_back();
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    return C;
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}
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int main() {
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    string a, b;
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    cin >> a >> b;
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    vector<int> A, B;
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    for (int i = a.size() - 1; i >= 0; i--) A.push_back(a[i] - '0');
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    for (int i = b.size() - 1; i >= 0; i--) B.push_back(b[i] - '0');
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    vector<int> C;
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    if (cmp(A, B)) {
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        C = sub(A, B);
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    } else {
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        C = sub(B, A);
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        printf("-");
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    }
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    for (int i = C.size() - 1; i >= 0; i--) printf("%d", C[i]);
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    return 0;
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}