#include <stdio.h>
int T(int n);
int main(void) {
int n=4,re;
re=T(n);
}
int T(int n){
switch(n){
case 0:
return 0;
case 1:
case 2:
return 1;
default:
return T(n - 1) + T(n - 2) + T(n - 3);
}
}
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