View Compilation Error

0_0_26617136_10345.cpp:6:1: error: 'LL' does not name a type
 LL solve(LL x,LL y){
 ^
0_0_26617136_10345.cpp: In function 'int main()':
0_0_26617136_10345.cpp:24:38: error: 'solve' was not declared in this scope
             if(x > y)sum += solve(x,y)-1;
                                      ^
0_0_26617136_10345.cpp:25:35: error: 'solve' was not declared in this scope
             else  sum -= solve(y,x) -1;
                                   ^