A person is swimming with a speed of $10 \mathrm{~m} / \mathrm{s}$ at an angle of $120^{\circ}$ with the flow and reaches to a point directly opposite on the other side of the river. The speed of the flow is ' x ' $\mathrm{m} / \mathrm{s}$. The value of ' x ' to the nearest integer is $\_\_\_\_$ .