f[x_, y_] := x^2 Sin[y] + y^3 Cos[x]^2
g[x_, y_] := Sin[x] Sin[y]^2 + x y Sin[x]
Show[ContourPlot[f[x, y], {x, 0, Pi}, {y, 0, Pi},
ContourShading -> None, ContourLabels -> All],
ContourPlot[g[x, y], {x, 0, Pi}, {y, 0, Pi}, ContourShading -> None,
ContourLabels -> All, ContourStyle -> Dotted]]
