View Compilation Error

0_0_22573948_1077.cpp: In function 'std::string add(std::string, std::string)':
0_0_22573948_1077.cpp:7:12: error: 'L' was not declared in this scope
     int na[L]={0},nb[L]={0};
            ^
0_0_22573948_1077.cpp:9:27: error: 'na' was not declared in this scope
     for(int i=0;i<la;i++) na[la-1-i]=a[i]-'0';
                           ^
0_0_22573948_1077.cpp:10:27: error: 'nb' was not declared in this scope
     for(int i=0;i<lb;i++) nb[lb-1-i]=b[i]-'0';
                           ^
0_0_22573948_1077.cpp:14:9: error: 'na' was not declared in this scope
         na[i]+=nb[i];
         ^
0_0_22573948_1077.cpp:14:16: error: 'nb' was not declared in this scope
         na[i]+=nb[i];
                ^
0_0_22573948_1077.cpp:18:8: error: 'na' was not declared in this scope
     if(na[lmax]) lmax++;
        ^
0_0_22573948_1077.cpp:19:37: error: 'na' was not declared in this scope
     for(int i=lmax-1;i>=0;i--) ans+=na[i]+'0';
                                     ^