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#ifdef CHECK_FUNCTION_EXISTS char CHECK_FUNCTION_EXISTS(); #ifdef __CLASSIC_C__ int main(){ int ac; char*av[]; #else int main(int ac, char*av[]){ #endif CHECK_FUNCTION_EXISTS(); if(ac > 1000) { return *av[0]; } return 0; } #else /* CHECK_FUNCTION_EXISTS */ # error "CHECK_FUNCTION_EXISTS has to specify the function" #endif /* CHECK_FUNCTION_EXISTS */