  The characterization of four new transiting extrasolar planets is presented
here. KOI-188b and KOI-195b are bloated hot Saturns, with orbital periods of
3.8 and 3.2 days, and masses of 0.25 and 0.34 M_Jup. They are located in the
low-mass range of known transiting, giant planets. KOI-192b has a similar mass
(0.29 M_Jup) but a longer orbital period of 10.3 days. This places it in a
domain where only a few planets are known. KOI-830b, finally, with a mass of
1.27 M_Jup and a period of 3.5 days, is a typical hot Jupiter. The four planets
have radii of 0.98, 1.09, 1.2, and 1.08 R_Jup, respectively. We detected no
significant eccentricity in any of the systems, while the accuracy of our data
does not rule out possible moderate eccentricities. The four objects were first
identified by the Kepler Team as promising candidates from the photometry of
the Kepler satellite. We establish here their planetary nature thanks to the
radial velocity follow-up we secured with the HARPS-N spectrograph at the
Telescopio Nazionale Galileo. The combined analyses of the datasets allow us to
fully characterize the four planetary systems. These new objects increase the
number of well-characterized exoplanets for statistics, and provide new targets
for individual follow-up studies. The pre-screening we performed with the
SOPHIE spectrograph at the Observatoire de Haute-Provence as part of that study
also allowed us to conclude that a fifth candidate, KOI-219.01, is not a planet
but is instead a false positive.
