At the 140th minute, he can take to climb up the well.
REASON..
1*5min = 5min he can climb up to 0+3-2 = 1m.
2*5min = 10min he can climb up to 1+3-2 = 2m.
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25*5min = 125min he can climb up to 24+3 = 27-2 = 25m.
26*5min = 130min he can climb up to 25+3 =28-2 = 26m.
27*5min = 135min he can climb up to 26+3 = 29-2 = 27m.
28*5min = 140min he can climb up to 27+3 =30., at this stage he never slipped back..!