Compilare: user.c: In function ‘multi’: user.c:16:7: warning: operation on ‘a’ may be undefined [-Wsequence-point] a = (a <<= 1)%MOD; ^ user.c: In function ‘main’: user.c:39:17: warning: unused variable ‘C’ [-Wunused-variable] long long A, B, C; ^ user.c:44:7: warning: ignoring return value of ‘fscanf’, declared with attribute warn_unused_result [-Wunused-result] fscanf(file1, "%lld", &A); ^ user.c:45:7: warning: ignoring return value of ‘fscanf’, declared with attribute warn_unused_result [-Wunused-result] fscanf(file1, "%lld", &B); ^ user.c:46:7: warning: ignoring return value of ‘fscanf’, declared with attribute warn_unused_result [-Wunused-result] fscanf(file1, "%lld", &MOD); ^