1844. Replace All Digits with Characters

class Solution {
public:
    string replaceDigits(string s) {
     for(int i=0; i<s.size(); i+=2)
     {
          int c=s[i]+s[i+1]-'0';
         char c1=char(c);
        s[i+1]=c;
       
     }  
   
     return s; 
    }
    
};