  The time-dependent $C\!P$ asymmetries in $B^0\to\pi^+\pi^-$ and $B_s^0\to
K^+\!K^-$ decays are measured using a data sample of $pp$ collisions
corresponding to an integrated luminosity of 3.0 fb$^{-1}$, collected with the
LHCb detector at centre-of-mass energies of 7 and 8 TeV. The same data sample
is used to measure the time-integrated $C\!P$ asymmetries in $B^0\to K^+\pi^-$
and $B_s^0\to\pi^+ K^-$ decays. The results are $C_{\pi^+\pi^-} = -0.34 \pm
0.06 \pm 0.01$, $S_{\pi^+\pi^-} = -0.63 \pm 0.05 \pm 0.01$, $C_{K^+\!K^-} =
0.20 \pm 0.06 \pm 0.02$, $S_{K^+\!K^-} = 0.18 \pm 0.06 \pm 0.02$,
$C_{K^+\!K^-}^{\Delta\Gamma} = -0.79 \pm 0.07 \pm 0.10$, $A_{C\!P}^{B^0} =
-0.084 \pm 0.004 \pm 0.003$, and $A_{C\!P}^{B_s^0} = 0.213 \pm 0.015 \pm
0.007$, where the first uncertainties are statistical and the second
systematic. Evidence for $C\!P$ violation is found in the $B_s^0\to K^+\!K^-$
decay for the first time.
