A rectangular structure of width $b=5m$ and height $8m$ is flooded by $7\mathrm{.}5m$ of water flowing normal to its leading face. $($directly into the front face of the structure$).$

If the water height at the rear of the structure is $6\mathrm{.}5m,$ what is the resultant hydrostatic force on the structure? $($ignoring the water on the side walls$).$

Give the answer in N$,($you do not need to input units, only the numerical answer$).$