If $\overrightarrow{\mathrm{b}}=3\hat{\mathrm{i}}+4\hat{\mathrm{j}}$ and $\overrightarrow{\mathrm{a}}=\hat{\mathrm{i}}-\hat{\mathrm{j}}$, the vector having the same magnitude as that of $\overrightarrow{\mathrm{b}}$ and parallel to $\overrightarrow{\mathrm{a}}$ is