func_code_string: #include <bits/stdc++.h>   using namespace std;   const int N = 20;   int t;   int n, s;   string str;   char n1[N];   char n2[N];   int a[N], b[N], c[N];   int main() {     cin >> t;     while (t--) {       cin >> str >> s;       int sum = 0, k = -1, pos = -1, flag = 1;       for (int i = 0; i < str.size(); i++) {         sum += str[i] -  0 ;         if (sum == s && flag)           pos = i, flag = 0;         else if (sum > s) {           if (pos != -1)             k = pos;           else             k = i;           break;         }       }       if (sum <= s || (pos != -1 && k == -1)) {         cout << 0 << endl;         continue;       }       memset(c, 0, sizeof c);       memset(n2, 0, sizeof n2);       memset(n1, 0, sizeof n1);       memset(a, 0, sizeof a);       memset(b, 0, sizeof b);       for (int i = k; i < str.size(); i++) n2[i - k] = str[i];       n1[0] =  1 ;       for (int i = 1; i <= strlen(n2); i++) n1[i] =  0 ;       int lena = strlen(n1);       int lenb = strlen(n2);       for (int i = 0; i <= lena - 1; i++) a[lena - i] = int(n1[i] -  0 );       for (int i = 0; i <= lenb - 1; i++) b[lenb - i] = int(n2[i] -  0 );       int i = 1;       while (i <= lena || i <= lenb) {         if (a[i] < b[i]) {           a[i] += 10;           a[i + 1]--;         }         c[i] = a[i] - b[i];         i++;       }       int lenc = i;       while ((c[lenc] == 0) && (lenc > 1)) lenc--;       for (i = lenc; i >= 1; i--) cout << c[i];       cout << endl;     }     return 0;   }   