#include <stdio.h>
#include <inttypes.h>
uint64_t mid (uint64_t a, uint64_t b, uint64_t res)
{
if (b == 0){ if (a > 2) return mid (a-2, b , res+1); else return res;}
if (a == 0){ if (b > 2) return mid (a , b-2, res+1); else return res;}
return mid (a-1, b-1, res+1);
}
int main(void) {
printf("%"PRIu64
, mid
(20, 13, 0)); return 0;
}
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