View Compilation Error

0_0_17836656_25661.cpp: In function 'int main()':
0_0_17836656_25661.cpp:93:58: error: invalid initialization of non-const reference of type 'long long int&' from an rvalue of type 'long long int'
         printf("Case #%d: %lld\n",++Case,solve(r)-solve(l-1));
                                                          ^
0_0_17836656_25661.cpp:44:4: note: in passing argument 1 of 'long long int solve(long long int&)'
 LL solve(LL &x)
    ^