$ gcc calc.c bigint.c -o calc
$ ./calc
-934834834934583458 * (847467494749 - 9364617634234234234234) / (1 + 123456789123456) Enter
70910403888588273104107053
$ gcc calc.c bigint.c -o calc
$ ./calc
-934834834934583458 * (847467494749 - 9364617634234234234234) / (1 + 123456789123456) Enter
70910403888588273104107053