View difference between Paste ID: 4itQpvfz and TeAgBTMc

-string operator+(string a, string b) {
+int sot(string s){
 	int ans = 0;
 	Fora(v, s){
 		ans *= 10;
 		ans += (v - '0');
 	}
 	return ans;
 }
 
 string tos(int x){
 	if (x == 0) return "0";
 	string s = "";
 	while (x){
 		s += (char)(x % 10 + '0');
-string operator-(string a, string b) {
+		x /= 10;
 	}
 	reverse(bend(s));
 	return s;
 }
 
 bool cmp(string a, string b){
 	if (a.length() != b.length()) return a.length() < b.length();
 	return strcmp(a.c_str(), b.c_str()) < 0;
 }
 
 string add(string a, string b){
     string ans = "";
     while (a.length() < b.length()) a = "0" + a;
     while (b.length() < a.length()) b = "0" + b;
     int carry = 0, rem;
     for (int i = a.length() - 1; i >= 0; --i) {
         rem = (a[i] - '0' + b[i] - '0') + carry;
         ans = (char(rem % 10 + '0')) + ans;
         carry = rem / 10;
     }
-string operator* (string a, string b) {
+
     return ans;
 }
 
 string sub(string a, string b){
     string ans = "";
     bool neg = 0;
     while (a.length() < b.length()) a = "0" + a;
     while (b.length() < a.length()) b = "0" + b;
-        for (int j = b.length() - 1; j >= 0; -- j)
+
     int carry = 0, rem;
-    for (int i = a.length() + b.length() - 2; i >= 0; --i) {
+
         rem = a[i] - b[i] - carry;
         carry = 0;
         while (rem < 0) {
             ++ carry;
             rem += 10;
         }
         ans = (char(rem % 10 + '0')) + ans;
     }
     while (ans.length() > 1 && ans[0] == '0') ans.erase(0, 1);
     if (neg) ans = "-" + ans;
     return ans;
 }
 
 string mul(string a, string b){
     long long sav[2050];
     for (int i = 0; i < 2050; i++)
         sav[i] = 0;
     string ans = "";
     int carry = 0, rem;
     a = "0" + a;
     b = "0" + b;
     for (int i = a.length() - 1; i >= 0; --i)
         for (int j = b.length() - 1; j >= 0; --j)
             sav[i + j] += ((a[i] - '0') * (b[j] - '0'));
     for (int i = a.length() + b.length() - 2; i >= 0; --i){
         rem = sav[i] + carry;
         carry = rem / 10;
         ans = char(rem % 10 + '0') + ans;
     }
     while (ans.length() > 1 && ans[0] == '0') ans.erase(0, 1);
     return ans;
 }
 
 string divnum(string a, int b){
     string ans;
     int idx = 0;
     int tmp = a[idx] - '0';
     while (tmp < b){
        tmp = tmp * 10 + (a[++idx] - '0');
    }
     while (a.size() > idx){
         ans += (tmp / b) + '0';
         tmp = (tmp % b) * 10 + a[++idx] - '0';
     }
     if (ans.length() == 0){
         return "0";
     }
     return ans;
 }
 
 int modnum(string a, int b){
 	string c = divnum(a, b), d = mul(c, tos(b));
 	return sot(sub(a, d));
 }
 
 int strgcd(string a, int b){
 	return __gcd(modnum(a, b), b);
 }
 
 string lcm(string x, int y){
 	return mul(divnum(x, strgcd(x, y)), tos(y));
 }