/in/bigint.c:8:1: error: return type defaults to 'int' [-Werror=implicit-int]
 main()
 ^~~~
/in/bigint.c: In function 'main':
/in/bigint.c:14:9: error: unused variable 'prev_result_2' [-Werror=unused-variable]
     int prev_result_2;
         ^~~~~~~~~~~~~
/in/bigint.c:13:9: error: unused variable 'prev_result_1' [-Werror=unused-variable]
     int prev_result_1;
         ^~~~~~~~~~~~~
/in/bigint.c:12:9: error: unused variable 'fibbonacci' [-Werror=unused-variable]
     int fibbonacci = 1;
         ^~~~~~~~~~
/in/bigint.c:11:9: error: unused variable 'i' [-Werror=unused-variable]
     int i;
         ^
cc1: all warnings being treated as errors