import java.util.*;


public class Solution {
    /**
     * 代码中的类名、方法名、参数名已经指定，请勿修改，直接返回方法规定的值即可
     * 计算两个数之和
     * @param s string字符串 表示第一个整数
     * @param t string字符串 表示第二个整数
     * @return string字符串
     */
    public String solve (String s, String t) {
        // wrITe code here
    }
}

@H_406_58@

// 没不出来，这个不对
import java.util.*;
public class Solution {
    public String solve (String s, String t) {
//         long num1 = Long.parseLong(s);
//         long num2 = Long.parseLong(t);
//         return "" + (num1 + num2);
        String res = "";
        int flag = 0;
        for(int i=s.length()-1, j=t.length()-1; i>=0 && j>=0; i--, j--){
            int numS = s.charAt(i); //自动转换
            int numT = s.charAt(j);
            if(numS + numT + flag >= 10){
                flag = 1;
                res += (numS + numT + flag) / 10;
            }else{
                flag = 0;
                res += (numS + numT);
            }
        }
        System.out.PRintln(res);
        return res;
    }
}

import java.math.BigInteger;
import java.util.*;
public class Solution {
    public String solve (String s, String t) {
        Biginteger bigInteger1 = new BigInteger(s);
        BigInteger bigInteger2 = new BigInteger(t);
        return bigInteger1.add(bigInteger2).toString();
    }
}

import java.util.*;
public class Solution {
    public String solve (String s, String t) {
        int sum = 0;
        StringBuilder result = new StringBuilder();
        int si = s.length() - 1;
        int ti = t.length() - 1;
        while (si >= 0 || ti >= 0)
        {
            if (si >= 0)
            {
                sum += s.charAt(si) - '0';
                si--;
            }
            if (ti >= 0)
            {
                sum += t.charAt(ti) - '0';
                ti--;
            }
            result.apPEnd(sum % 10);
            sum = sum >= 10 ? 1 : 0;
        }
        if (sum > 0)
        {
            result.append(sum);
        }
        return result.reverse().toString();
    }
}

import java.util.*;
public class Solution {
    public String solve (String s, String t) {
        int len1 = s.length();
        int len2 = t.length();
        int max = len1;
        if (max < len2) {
            max = len2;
            s = padding(s, max);
        } else {
            t = padding(t, max);
        }

        StringBuilder sb = new StringBuilder(max + 1);
        int add = 0;
        for (int i=max-1; i>=0; i--) {
            int num1 = s.charAt(i) - '0';
            int num2 = t.charAt(i) - '0';

            int sum = num1 + num2 + add;
            sb.append(sum % 10);
            add = sum / 10;
        }
        if (add > 0) {
            sb.append(add);
        }
        return sb.reverse().toString();
    }

    private String padding(String s, int max) {
        if (s.length() == max) {
            return s;
        }
        StringBuilder sb = new StringBuilder(max);
        int gap = max - s.length();
        while (gap > 0) {
            sb.append('0');
            gap--;
        }
        sb.append(s);
        return sb.toString();
    }
}

import java.util.*;


public class Solution {
    /**
     * longest common substring
     * @param str1 string字符串 the string
     * @param str2 string字符串 the string
     * @return string字符串
     */
    public String LCS (String str1, String str2) {
        // write code here
    }
}