Maximum number of random variables to make pairwise correlation coefficient less than C

Question

Assuming N random variables $X_1, X_2, ..., X_N$, each has $m$ samples, (e.g. $m=3$). what is the maximum N such that all pairwise sample correlation coefficients $\rho_{X_i, X_j}$ are less than some constant $C$? (e.g. $C=0.6$)