Find the minimum cost
if ( ( s1 [ i ] == '1' && s2 [ i ] == '2' ) || ( s2 [ i ] == '1' && s1 [ i ] == '2' ) ) cost += min ( d , min ( a , b + c ) ) ; else if ( ( s1 [ i ] == '2' && s2 [ i ] == '3' ) || ( s2 [ i ] == '2' && s1 [ i ] == '3' ) ) cost += min ( d , min ( b , a + c ) ) ; else if ( ( s1 [ i ] == '1' && s2 [ i ] == '3' ) || ( s2 [ i ] == '1' && s1 [ i ] == '3' ) ) cost += min ( d , min ( c , a + b ) ) ; } } return cost ; }