#include <stdio.h>

 int main(void)
 {
 	int nr, v[200], c = 0;
 	FILE *in = fopen("nrtri.in", "rt");
 	FILE *out = fopen("nrtri.out", "wt");
 	
 	fscanf(in, "%d", &nr);
 	
 	for (int i = 0; i < nr; ++i) {
 	     fscanf(in, "%d", v[i]);
 	}
 	fclose(in);
 	for (int i = 0; i < nr - 2; ++i) {
 		for (int j = i + 1; j < nr - 1; ++j) {
 			for (int k = i + 2; k < nr; ++k) {
 				if (v[i] + v[k] >= v[j] && v[i] + v[j] >= v[k] && v[k] + v[j] >= v[i])
 			       c++;
 			}
 		}
 	
 	}
 	fprintf(out, "%d", c);
 	fclose(out);
 	return 0;
 }